Isn't this machine just a Jasic-badged version of the ancient WSME-200 analogue AC/DC TIG? They can be bought for £380 in UK - about 700 AUD.you can buy a new one for $1,800.00 AUD
You can also disconnect the yellow cable and measure between yellow wire to the black.
Tested it and it is on about 10.4V on MMA and Tig with the trigger engagedDisconnect or cut the yellow wire and measure between black/yellow to check if there is a problem at the bottom board.
As i read elswhere mosfet circuit needs about 9-10V to perform.
Also please test it in MMA mode!