Just been playing around with this Acer (Aspire 4930), which is tricky as screen is cracked and hard to read but with the locked drive in and a Linux CD in the drive, without changing boot order in BIOS I can still boot to CD by pressing F12 (Boot Menu) at the same time that the Press 'F2' to Enter Setup notice appears on screen and boot successfully into Linux. Keys should be the same for your Lenovo, F2 & F12?
Have to be bloody quick though or the HDD Password screen comes up. If you're wanting to 'run diagnostics' on the drive from CD to try and find the password, give up now and don't waste more precious time, send it to a recovery specialist and ask them to remove the password from the drive.
I went through all of this a few weeks back (same Acer) and ended up getting in touch with pcimage (from here) who is able to remove the pw for me via hardware, I'm not interested in the data (it's just a few TV eps & some security progs I was playing with) but if you need the data it's more expensive as it's harder to do, I am reliably informed, and you'll probably have to prove that it's you machine/data too for legal reasons.
I've been searching for your BIOS options and it seems there aren't too many I think you have one of those stripped down BIOS's that gives you just the very basics?
Best bet as already said, reset BIOS, get a new drive/have pass lifted and chalk it up to experience, making sure to protect any future laptops you loan out yourself so the ******* can't do it again.

No chance of getting the ex student to own up and give you the password?
S