ELegoo Mars 2 Pro won't starting printin and starts loud hum with vibration

[cliffyk]

Remove the platen assembly and resin vat, then press the "Home" button. If the trolley descends, stops, rises a bit, then falls slowly and stops (as shown below), then the problem is the manner in which you are adjusting the build plate--or some irregularity in the resin vat or FEP.

normal trolley travel to Home position:
click here for .mp4 video (43 MB)

The platen may be shifting as you are tightening the lock screws--make 110% certain the FEP is clean and all the FEP retainer screws are properly seated.

BTW the platen lock screws just need to snugged up, not tightened like a lug nut.