Anet A8 home position below bed, past stop

When I home Z, the nozzle ends up below the bed, past the stop. The stop had smaller screws when installed, and this knocked the stop down so I put more heavy duty screws in. I bend the stop a bit to get it in a better position (it has drilled holes, no slots for adjusting) and the stop works and puts the nozzle in a good position when I move Z down with the buttons. It's just when I hit home that it ignores the stop and keeps going. Why is home disabling the stop? It seems like there should be a way to adjust where the home position is, but I can't find any way to do that. I tried flashing the board to Marlin, but it keeps failing, and I haven't yet been able to figure out why.

board is probably already using an early version of marlin - but like mine (probably), might lack a bootloader.

Sounds like maybe you've damaged the endstop. try a new one and check the wiring. Sometimes the connectors come lose inside the rubber shrink tubing where they connect to the stop itself.