I have found a faulty diode that needs replacing; the only markings on it are:
I managed to find another working identical diode on the PCB which I have taken off and put in one of these cheap "mega328 transistor testers"
Uf = 765mV , C = 38pF
What is Uf (is it supposed to be forward voltage?)?
Partial schematic of where the diode is located
The a1015 transistor was faulty and all 3 pins were shorting.
The D152 diode next to it was faulty too.