if u open it, as u said u hold the f2 and f4 and put the password to login to the menu, now the problem is ,the store authorized certificate will be erased, so he need to put AUTHKEY to make it work, if u screw lil more vx670 will say DOWNLOAD NEEDED , u can remove the tamper error thats not a probelm but u cant use the same tamper error cleared pinpad to the store, the verifone technician has to reprogrammed the pos to work it back, i even have the key to reset tamper error message from verifone sc5000 but ther is no use its useless, we just have to keep it our house showcase