I am selling my TF700 and wanted to return to stock before selling it(currently have chromi-x 5.3). I downloaded the 4.2.1 stock rom from the Asus website, unzipped, copied the rom zip to the sd card of the tablet. Rebooted to TWRP and installed the zip. Everything seemed to install fine. The tablet rebooted and the lock screen came up. But when I swipe to unlock, I get a 'Unfortunately, Launcher has stopped' message. I can hit Ok, but the message just keeps repeating. Any help would be greatly appreciated.
I assume you downloaded the correct SKU since you did everything else correct.
My guess is: a bad flash.
Try booting into recovery. If you get the dead Android, the stock recovery installed fine. If you have the Asus firmware on your microSD, rename it to EP201_768_SDUPDATE.zip and boot into recovery. It should recognize the file and flash it.
Alternatively, you could flash TWRP in fastboot and flash the firmware again.
Side note: I will never understand why people flash the tablet back to the lousy stock rom to sell it.... Anybody doing the least bit of research should know that this tablet with CROMi-X installed is 10x better - that actually only custom ROMing makes it useable.....
I would offer it here on the XDA market as: "TF700 in mint condition with a clean installation of any bootloader/recovery/kernel/rom you desire"