Usual disclaimer: I'm not responsible for bricked tablets or loss data. Make a backup of any important file that is in your tablet.
What I'm writing here is what I did for my device and it worked. Here is how I did for my Acer a500 using windows 7. Mileage varies a lot. Some people don't have any problem, some have a lot.
You have to be on stock ICS (android V4 from Acer) to do that. I did it with my tablet up to date (by doing all Acer upgrades over the air).
First of all, here are some parts that I understood; if I'm wrong please let me know and I'll make some corrections.
bootloader: fisrt part of software loaded by de device. It selects which part (recovery or system) should be loaded next. Our a500 comes with a bootloader that checks if the system is still an Acer one. If not, it doesn't boot. Skrilax_CZ wrote one that do wonders!
Recovery: This part of software is the one that let you upgrade, change rom and do some other stuff like formating partitions. I use Thor's version since it has a lot of features work fine with any of his roms.
In order to install a new ROM, you need an unlocked bootloader, a custom recovery (powerfull enough), the rom of your choice and a PC running Windows.
The tool I used to do all this stuff is called afterota. Here is what you need to do this installation.
1) Acer divers. I got mine from here: http://us.acer.com/ac/en/US/content/drivers
, I chose Tablet, ICONIA A, A500 and android 3.2 HoneyComb.
2) Afterota tool. I got mine from here: http://forum.xda-developers.com/showthr ... ?t=1675939
, you can download both versions but I only used the complete version (file that is 104Mb). It downloaded me a weird file name which I renamed to afterota.zip and it worked. Please validate it it's really a zip file if you have to rename it.
First thing to do is getting rid of already installed drivers on your PC unless you are really sure these are the ones from Acer. If not, make sure to remove them and install Acer ones. You can also use afterota tool to help you on that (in tab called Info).
Unzip afterota to a directory of your choice on your PC.
Disable UAC, you can re-enable it after installation. Here is one way: http://windows.microsoft.com/en-ca/wind ... =windows-7
If you are under Windows 8+ (8,10,...) and you can't install Acer drivers, please refer to Freightyard post which give a nice trick to get them installed: viewtopic.php?f=10&t=2196&p=56813&hilit=update#p56813
First of all, you need tablet information. Afterota will retreive these informations (like SBK) and save theme to a file. Save this file carefully, it may save you from lot of troubles later. To do that, in afterota tool, go to the first tab called Info and click on "Save Values".
Once this done, you can install a custom recovery and a custom bootloader. I used the standard one called bootloader Ics v3.14.8 + Recovery Twrp v2.1.3 and you can also try Ics v3.14.8 + Recovery Thor v1.7.3; again some people tried different version and got different mileages. To do the installation, select "standard" tab and click the opton of your choice, don't forget the first option shouldn't be selected since it's for HC and you are on ICS. Follow carefully all steps.
Even if it says successfull, it doesn't mean it did everything right the first time, some people reported they had to do it more than once and using both versions (Twrp or Thor's). But if everything went fine, you should still be able to start your tablet in ICS (as before) and also start the installed custom recovery. To test your recovery, turn off your tablet. Once it's off, push volume up and hold it (volume up is the closest side to the power button) and turn on your tablet using the power button (all in the same time). If it's booting in a custom recovery like TWRP or Thor's, your done for this part. This is the most difficult one.
From here, you will need:
1) A micro sd card big enough. It must be formatted in fat.
2) Thor's recovery. You will find it here. viewtopic.php?f=8&t=1490
3) Skrilax_CZ v9 bootloader if you want. If you have V8 bootloader, this piece of software is not required. You can see bootloader version at tablet startup. You will find it here http://forum.xda-developers.com/showthr ... ?t=1619913
, take the update.zip for CWM.
4) A ROM of your choice, but this part can wait.
- Put all those download files onto your micro sd card. Validate MD5s when available.
- Turn off your tablet
- Insert the sd card in your tablet
- Boot in recovery (power + volume down -- closest to power button)
- Install Thor's recovery by selecting the Thor`s recovery zip file (Thor's TWRP REV 2.0 beta4).
The following part is not required if you have bootloader V8.
- once done, reboot your tablet in recovery again
- Install Skrilax_CZ bootloader by selecting the zip file
Now it can be a good idea to do a Nanddroid backup. Make sure you have enough free space on your sd card. To do the backup:
- boot in recovery again
- Select backup
- Let the default selections, usually these are good. Make sure it says "Storage: external_sd..." on the bar at the right, so it will put this backup on your micro sd card. If it's not external_sd, click in the "storage" bar and select external_sd.
- Let it do it's job, it may take a while.
To install your new custom rom, download it from tegraowners site (this site). The current stable versions are 4.4.4 V23 final, CM12 5.1.1V4 or OmniROM 5.1.1V9. THIS WILL ERASE ALL YOUR FILES ON YOUR TABLET, please backup your photos and all your files before proceeding.
- download the rom of your choice and check MD5.
- dowload the gapps that goes with it, usually there is one proposed with the ROM. Use the gapps that macthes the ROM, it will save you a lot of troubles.
- put the downloaded files on your sd card
- insert the sd card in your tablet
- reboot your tablet in recovery
- format/wipe data partition, to do that, click on Wipe. You have the choice to go to f2fs which in my case helped a lot on repsonsiveness; but this is not required. To just format, tap on format data. To format in f2fs, tap on Advanced wipe, tap cache and data (these 2 are enough) to have them selected, tap on repaire or change file system and select f2fs. Let ti do its job.
- once done, go to twrp home screen and select install.
- select the one rom of your choice (zip file)
- click on add more file
- select the gapps that goes with rom and proceed to installation
- Once installation is done, click on Clear dalvik cache.
- be patient, the first time is a long boot.
It may take up to 10-15 minutes. If it's take more than that, something went wrong. You can retry.