Good morning, the Tr of isolated gate that you replace must be original or taken out of another recycling chassis, before placing you must put their dissipative paste, and check that you should not heat the heatsink of the changed tr say in about 2 minutes, you turn on after 2 minutes you turn off the power and you touch the heatsink, if it heats up too much in that period it is because something is wrong, and they will burn again, in that case check electrolytic and surface capacitors of those surroundings, also before measure how much your source delivers, voltage of Vs, Va and 5v, that you do by disconnecting all the connectors and leaving the source alone and there you measure those voltages mentioned that are in the source connector, you will hear that the relay sticks when connected. After measuring the source connect all the connectors by precaution, because if you leave something unconnected you can damage other stages, it also places all its Ysus screws and plate that you take out and test, the absence of any screw can cause it to break down The same plate or another.