How to remove SVP without knowing on L420?

Back before the Intel Boot Guard machines, you could find the ATMEL chip and short 2 lines out quickly (I don’t reveal these to avoid being caught up in a legal nightmare, but it’s been mentioned by others) or use a specific tool found online to clear this up. However, that hasn’t worked since the XX40 series :(. It only works on machines from the 390E to the XX30 series (with a few exceptions) since these are pre-Boot Guard.

These newer systems need to be reset with software only Lenovo has access to so you preserve the ability for the system to boot correctly - it exists, so it’s a matter of how willing they are to deny it’s something they can do. If you do it wrong on these, you’ll trigger the tamper checks done by the ATMEL chip and lock the machine out, or kill it because of a bad private key check thanks to Boot Guard. It really does depend but you’re in deep trouble either way and will have no way out besides a new motherboard. We can’t fix the tamper lockout, even on pre-Boot Guard systems — it was ALWAYS A NEW BOARD. For these, you are going to need a motherboard or see if Lenovo will finally admit it can be done in software but refuse to admit it. HP admits it was possible, so they’re lying to charge the motherboard repair rate. You will also need a receipt to prove ownership.

The security chip tampering problem really didn’t matter much before since while it could be triggered, it wasn’t a common problem outside of the few (paranoid) corporate/gov’t machines that actively set it to check. These newer machines either do not boot due to a failed private key check or lock the system out from booting at all.