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I picked up a used dirty novak t4 untested. It had frayed receiver wire but otherwise intact. I replaced the wires after cleaning everything up and soldering on fresh connectors.

Plugged in to rx with a battery and it powers up the rx and servo no problem.
I set the tx direction, adjusted the center and high pots on the esc so the light goes on and off as it should.
Everything looks like it is working fine so I plugged in a known working motor and nothing happens with throttle input on the tx.
The esc light goes on and off indicating throttle, full throttle, and brake, but no power to the motor.
The esc doesn't get warm at all, no visible signs of burnt mosfets.
If I disconnect the rx and with the case open Jump the + bat wire to the Gate lead on a couple of the forward fets the motor receives power.

There are no burnt traces, loose wires or bad solder joints that I can see.
I'm at my limit of electronics knowledge.

Does anyone have any suggestions for how to repair this ESC?

It actually looks quite nice now all cleaned up, might just have to be for a shelfer that isn't going to get run anyway.

it sounds like whatever components are in series with the gate drive are blown out, which is odd, but who knows. where you applie + to get the motor to spin, look at the components and see what is in series, probably a resistor, I believe the drive circuit might have a boost voltage and that may be bad, there are a few transistors in that path that could have gone bad.

I guess you're all talking brushless these days but 'not' in this case, but I got a £8 320A off ebay, seems to work fine. Although the first one received had a dodgy on/off switch but the vendor sent a replacement, now I have two after repairing the dodgy ones switch, no extra cost from vendor.
point is unless its worth more than $50/£40 is spending more than an hour on it is a waste of time. with so much 'inside' silicon chips it looks like a bin job.

thanks for the input. I looked at the circuit again. tested a few of the resistors in series and they look good. Looks like a chip may be bad. Ohh well. it will look nice on a display car.

yeah, you would have to put a scope on it to see if things are switching as necessary. otherwise, she'll look good on the shelf.

I have a minty T4 case from an ESC that sounds similar to yours, if you need a case for display purposes. Its such a let down when you buy an electronic device and it doesn't work.