No Power.

The gate of a transistor is the input terminal. It controls the flow of current between the collector and emitter terminals. The missing pad on the gate of Q2 is likely connected to the main power board via a bus wire. The bus wire is a common connection point for multiple components on the board.

To find where the bus wire leads to, you can use a multimeter to trace the wire back to its source. The multimeter should be set to the "ohms" setting. Touch one probe of the multimeter to the pad directly in front of the gate pin of Q2. Touch the other probe to each of the pins on the main power board until you find the one that has continuity with the bus wire.

Once you have found the pin that the bus wire is connected to, you can place a jumper wire from the gate of Q2 to that pin. This will restore the functionality of Q2 and allow the power inverter board to operate properly.

It is important to note that working on electrical equipment can be dangerous. If you are not comfortable working with electrical wiring, you should call a qualified technician to help you repair the HP 2509m Power Inverter Board.

Here are some safety tips to keep in mind when working with electrical wiring:

Always turn off the power to the circuit before working on it.

Use a non-contact voltage tester to make sure that the power is off.

Be careful not to touch exposed wires.

Wear safety glasses to protect your eyes.

I hope this information is helpful.