have you try to follow the admin guide yet? https://drive.google.com/file/d/0BynPQojkIX8rcU5rWlg5clYzYmM/edit?usp=sharing
:mrkrad
Your advice regarding the CF card is good but not in this case. Regarding the backdoor during boot, i'm not aware of such an option, but it might be there. Just let us know if you found it.
:d2000
Unfortunately from my knowledge (after opening Mellanox 4036 switch) there is no CF card. The flash is on the MB. In the 4036 there is just a SODIMM socket with a ram module which can be swapped.
I think you should try all the options you have in the manual of 2.1 firmware version / or manual of 3.91 firmware version like :markpower28 suggested. There are some major changes between some of the firmware releases on the path from 2.1 to 3.91.