Gael Holmes, Software Development team blogged about the T400 & the beep beep beep error.  Check out her post and the additional tips from Frank on reseting back to factory.. 


Comment from Gael's blog -


Hi Gael,
I had the same "Morse Code" problem on a T400 and thought it was a one-of-a-kind..


But, I have some good news for you... there is a Lenovo BIOS update that addresses this and it worked me...


As to the question of how to get the ME back to factory default, here isn the process I use:


In BIOS, select Config-> Intel (R) AMT-> Intel (R) AMT Control- Disable ... exit BIOS and reboot


Then repeat the above enabling the AMT control, and you will be back at factory default- PWD is "admin" again