How can I have system certificate android?

Android tablet is hung up on a system update

• I've got a refurb ASUS ME173x tablet here, that I bought to give my one of my kids for Christmas. It's actually one of four identical tablets that we bought for our four (non-identical) kids. I've updated three of them to Android 4.2.2, per the notification that popped up on each. This last one, though, seems to be hung up on the actual installation. Its been hung up on the "installing system update" screen for about three hours now. It seems to be stuck in a loop. If I short press the power button, it gives me a list of what's going on :"installing update . . . Verifying current system . . . removing unneeded files . . . patching system files . . ." and so on. I can hold the power button and get the screen to turn off (though I don't know if the unit is actually powered down) but when I turn it back on, after the ASUS splash screen, it goes immediately to the "installing system update" graphic again, and everything keeps doing the same thing. I can't boot it into recovery mode by holding the 'volume up' button with the power button either. ASUS tech support suggested that I let it keep running to see if the update eventually installs. I've got a square trade warranty on it, so it won't be a loss, but we'll be caught a little flat-footed for Christmas morning at this point. Any ideas about how to reset this thing or get it off high-center? Thanks!

• Answer:

  If you can find the system image files, you can boot it into fastboot mode and reflash the firmware from there using either the generic Android fastboot utility that comes in the SDK or the Asus fastboot utility you can get from their site. Unfortunately, I'm on my phone right now and a quick Google didn't turn up any factory images for it. Alternatively, doing a factory reset as described http://www.asus.com/support/FAQ/1006239/ might get it back to normal.