Ah, any chance that someone has turned every adjustment screw inside randomly while watching the scale on a wattmeter?
This tends to shut down a receiver.
Just the same, finding out how far "downstream" from the antenna to find the problem starts at the receiver's IF filter. For me it does, anyway.
Find the crystal filter, near the center of the pc board. Now take your "Manual Digital Signal Injector" and touch to the input and output solder pads under the crystal filter.
Yeah, that signal injector. Lay your finger along the shaft of a small screwdriver. Touch the tip to a sensitive spot on the circuit board, and you'll hear either RF noise from your surroundings it it's an RF circuit, or an audio hum, if it's an audio circuit.
And if you can't get any noise from the speaker this way, that points to a problem downstream from that point in the radio.
If you get loud raucous noise from one signal pad under the filter, and somewhat less from the other one, this points to the next stage upstream for the answer.
73