Default [Q] A500 flashing fails
I am not sure of the best place to post this. I am having trouble installing loader/ROM on an Acer A500 tablet. I have read many of the posts here and in other forums and have tried several of the suggestions/guides. I think I am just digging the hole deeper and need some guidance on the path I should follow at this point.

The tablet is running Android 4.0.3 (Acer_AV041_A500_1.033.00_PA_CUS1), which has been completely stock and not rooted up to now. I followed directions on several postings (mainly by dibb_nz) on this forum, but have not been successful.

Here's how far I got and where I went off the rails.
I rooted it using SuperUser.
I collected the CPUID and got the SBK number.
I downloaded/installed Acer drivers and Andriod SDK.
I downloaded APX_v0.4A-flashTool-500Manager1.0.2_(1) and ran A500Manager and found that it could get info from the tablet.
I ran A500APXFlash, downloaded bundle 17, entered the SBK.
I manually put the table in APX mode, confirmed it is the Windows system tray (APX Device) and A500APXFlash reported it in that mode.
I proceeded to flash (in A500APXFlash). Here is where it went off the rails.
It hung at some point, but I can't recall exactly where (I've done many things since), but it was it was something like formatting the flash. I let it go for an hour and finally killed everything and rebooted the tablet.

I tried many more things, but always ended in failure. One was manual flashing with nvFlash. Below are the highlights of the batch file output to show how far it got:
Code:
Enter your SBK: <removed for security reasons?
   *    Make your choise:                                   *
   *(4) ICS bootloader V8 with Thor-1.7.3 NEW cwm(touch cwm)*
   *              with its compatible recoveries.           *
(1  2  3  4):4
Loading bootloader...
nvflash --bct bct.bct --setbct --bl bootloader_apx.bin --configfile flash.cfg --odmdata 0x300d8011 --sbk 0xA88B1E00 0x9726AB01 0xD76C4F03 0x00022103 --sync
Nvflash started
rcm version 0X20001
System Information:
   chip name: t20
   chip id: 0x20 major: 1 minor: 4
   chip sku: 0x8
   chip uid: <removed for security>
   macrovision: disabled
   hdcp: enabled
   sbk burned: true
   dk burned: true
   boot device: emmc
   operating mode: 4
   device config strap: 0
   device config fuse: 0
   sdram config strap: 0

sending file: bct.bct
- 4080/4080 bytes sent
bct.bct sent successfully
odm data: 0x300d8011
downloading bootloader -- load address: 0x108000 entry point: 0x108000
sending file: bootloader_apx.bin
| 714981/714981 bytes sent
bootloader_apx.bin sent successfully
waiting for bootloader to initialize
bootloader downloaded successfully
failed executing command 25 NvError 0x120002
command failure: sync failed (bad data)
bootloader status: partition table is invalid, missing required information (code: 14) message: nverror:0x4 (0x4) flags: 0
During the above, the tablet said "Acer Iconia APX mode."

At one point I tried installing the CWM loader (I think it was that one). I also ran the Android adb program and was able to talk to the tablet through a command prompt.

Somewhere along the line, the Windows system tray driver report began saying "Acer USB Boot Recovery Driver" instead of "APX Device." I'm not sure when or what I did to cause it.

Another change in behavior is that the recovery mode boot (Power+VolDn) used to result in a dead robot icon. Now it looks like it is doing "SD update cmd: recovery" which fails (I put no SD card in it).

It appears that somewhere along the line (early in my trials) the BCT might have gotten wiped out and I cannot find a copy of it. I have seen various places where flashing hangs during a format or a download operation.

I have tried as much as I dare without help (maybe too much). At this point, by tablet is not bricked -- it still boots to Android 4.0.3. But I would like to restore it to where it was and then try the process again.

I have been trying to do the Timmy Dean EUU recovery to stock, but I have not been able to get the files. It seems that most of the links are either broken, or go to what lools like some pretty shady places. I'm not sure I should even be trying this route and, if I do, which EUU I should attempt.

I am fluent in Linux and have a Ubuntu 12.04 (VM) I can run if that's the best approach. I am also somewhat familiar with ARM Linux and the Marvell and TI-OMAP boot processes if any of this is useful. I am a complete noob on Android and the various ROMS, Loaders and mods. In fact, at this point, I'm not even sure what state tablet is in -- what loader is there, what has happened the flash ... -- or how to find out.

Thanks for whatever help/guidance you can give me.