topic Re: Chromebook Repair Screen? in Peer-Peer Topics

Chromebook Repair Screen?

MattDPenn — Wed, 08 May 2024 17:31:18 GMT

Greetings everyone,

This morning I encountered a student's chromebook that had gone to a OS "Chromebook Repair" screen of some sort that looked like was designed for testing components. I didn't have a chance to play around with it as I wanted to get the student rolling again so I selected exit and the chromebook went to the normal login screen.

Looking around I'm not finding any info about how to get to this screen normally. The most I can find is the screen is related to a factory OS image, that would then be auto-deleted afterwards, and would need a factory SHIM to get to. As far as we can tell this chromebook hasn't been out for repairs.

Anyone else have ideas?

Re: Chromebook Repair Screen?

NielsBrockmeier — Wed, 08 May 2024 17:38:50 GMT

A while ago, not exactly sure how long but around a year I think, a few factory SHIMs were leaked to the public. This was a whole happening as it meant students could unenroll (locally for the device) and thus get around restrictions. So if this student figured out a way to get a working SHIM they could have messed with it and gotten that screen.

A quick search led me to SH1MMER https://www.google.com/amp/s/www.theregister.com/AMP/2023/01/30/chromebook_exploit_sh1mmer/

Re: Chromebook Repair Screen?

ddelboccio — Wed, 08 May 2024 17:44:17 GMT

pressing ESC + REFRESH + POWER will get you to the recovery screen, if that is what you were seeing.

Re: Chromebook Repair Screen?

MattDPenn — Wed, 08 May 2024 20:14:59 GMT

It's not the standard recovery screen. At the top it'll say Chromebook Repair, not recovery, and it'll do some sort of verification before giving you the option to continue or exit.

Re: Chromebook Repair Screen?

MattDPenn — Wed, 08 May 2024 20:19:45 GMT

It's a possibility. I will note that it went to the normal login screen for our district whereas I would have assumed that if they tried SH!MMER that it would have been factory reset. Unless their attempt was unsuccessful perhaps.

Re: Chromebook Repair Screen?

Kim_Nilsson — Mon, 13 May 2024 14:23:11 GMT

It's worth noting that on very recent versions of ChromeOS, and perhaps only on Chromebook Plus devices, the Recovery screen has been massively updated and is very different from before.

Re: Chromebook Repair Screen?

MattDPenn — Mon, 13 May 2024 14:37:12 GMT

We're on LTS v114 and the chromebook in question doesn't meet the Chromebook Plus hardware requirements by a mile.

Re: Chromebook Repair Screen?

mhermmsd — Wed, 15 May 2024 18:19:56 GMT

It's called the SHIMLESS repair screen and is available on some models. You can access by holding power and pressing Refresh key 3 times.

Re: Chromebook Repair Screen?

MattDPenn — Wed, 15 May 2024 18:25:58 GMT

That's the ticket. It's strange that this nugget of information doesn't seem to be published anywhere given that it would be useful for schools running their own repair workshops. The feature appears to be at least a year old if some of the old topics I've found from people who accidently got the screen are anything to go by. Unsure how useful this would be in normal repairs but I'll have to make a point to check it next time I do a part swap to see if it actually says anything. Thank you.

Re: Chromebook Repair Screen?

ddelboccio — Wed, 15 May 2024 18:27:48 GMT

I just tried it on a 3 year old HP Chromebook 11 G8 EE and it worked. However, I'm not really sure what the purpose of this option is?

Re: Chromebook Repair Screen?

MattDPenn — Wed, 15 May 2024 18:37:02 GMT

If I don't miss my guess I believe it's for allowing a "non-approved" part to be used in a chromebook, or at least alerting the person repairing the chromebook that they may have used a bad part. From some other topics I had found while searching it's implied that you used to need a SHIM factory key to make certain repairs which is probably what led to the SH1MMER exploit when some of those factory keys got leaked. I'm thinking that Google implemented this SHIMLESS repair option in an attempt to reign in the need for factory keys where they really shouldn't have been needed.