The average Joe residential AC guy would not have a clue. You need to find a shop that does commercial refrigeration, and take it in.
Did you check if that bypass valve is dumping hot gas? You can do that by touch, the discharge line comes up and is piped to the inlet of the condenser but there is a Tee fitting with the hot gas solenoid valve on the branch. The discharge line is hot as also the shell of the rotary compressor. If the HG bypass valve is closed for allowing cooling, the line coming out of that valve should be just warm and further away should be cool. If the line is hot all the way of course that means the valve is open for some reason, either by the control system, bad coil or internal leaking. The first two can be fixed, the third requires opening the sealed system and replacing the valve.