Lenovo Thinkpad Tablet 1". Some editions of this Android Tablet has the bootloader locked. So, when Android miss behave and the recovery menu gets broken, the user does not have access to recover the tablet because the bootloader is locked by the manufacturer.
The only solution that Lenovo gives you is to pay for a new motherboard (if you are not under warranty). Changing a hardware components because of a software error? Sounds strange but that's the "magic" of the locked bootloaders.
After that I started to escalate inside Lenovo. I was put in contact with the "QA Team" in North America. After giving me some hope that they are going to check the problem and look for a solution I got this response:
"Hi Mr. Iturbide. I apologize for not responding sooner, but I wanted to review the feedback with the software engineers again.
The only solution Lenovo has to offer for this issue is to replace the motherboard. This is due to the fact that portions of the Android image contain Lenovo proprietary code. Additionally, there are licensed and DRM protected content that cannot be shared.
I do apologize for the inconvenience caused by this issue, and understand you feel we are over-correcting. Your feedback will go into future consideration as we develop our next line of consumer products.
Thanks for your support and please do not hesitate to contact me in the future.
Yes, the evil DRM software/content is the reason why Lenovo can not open the bootloader keys to the public. In other words, you can not fix your tablet for this software problem, you need to change (and pay) the mainboard.
So, the Thinkpad Tablet is just one example why you have to stay away from "Locked Bootloaders" on the Android platform and DRM protected Software/Content.
Locked Bootloaders + DRM protected content = Can't recover from Brick.
On my case (after more than 120 days bricked) Lenovo accepted to replace my motherboard free of charge, and I'm still waiting for the part that should arrive to my country on July 25 (2013). But there is no warranty that in the future other software problem will cause another brick, plus all the other Thinkpad Tablet owner that has a locked bootloader are under the same risk.
Take Care !!!
Sources: Lenovo Forum.