try to help help out a few pics of the mechine the reason or how its not working and any back info on what it was doing before rg was working fine it just xyz or ive just got it given by a mate that said does not work
Is the machine still under warranty? If so, return it to the supplier and ask for a replacement or a refund.
I'm afraid that amateur repair of an inverter welder is very difficult, if not impossible.
The problem issues include no circuit diagram, high voltages inside ( 325v DC ), high operating frequency, unmarked, unknown, unobtainable components, surface-mount construction, and high component density.
Probably the most you could do is a visual internal inspection. Power off and disconnect the input power cable. Wait a few hours for any voltages held in charged capacitors to decay, then remove the casing. Look for loose or badly-seated plugs and push-on tags, burnt components, loose or corroded connections, "dry" solder joints, and loose screws or bolts on the high-current wires and busbars.
The electronic logic that controls the overheat indicator may be defective, or maybe that indicator is also used to indicate a general fault, not just overtemperature. However, if the error is a genuine fault in the overheat detection, it may be possible to fix it.
Older equipment would use a thermostat to protect against excess temperature:
This device would be screwed or clipped to a heatsink. If it gets too hot, the internal contact between the two tags will open. Sometimes they stick open, but can easily be bypassed by simply short-circuiting the two tags together.
A newer machine, such as an inverter, will probably use a thermistor, glued or clipped to the main aluminium heatsink:
If you can locate the thermistor, the next step is to measure the resistance ( out of circuit ), then identify it, then replace or bypass it. The resistance when cold is probably supposed to be somewhere between 500 Ohms and 10K Ohms. This value may increase or decrease with temperature ( positive or negative temperature coefficient ). Depending on what you find, you could try a 1K resistor as a quick test.