I’ve noticed the wire coming from the gauge is crushed under the fuel tank strap could this have broken the insulation shorting it out ?
If you've got a diode tester function on your meter, you know, the one where you touch the probes together and it beeps... (that indicates short circuit) you can put one probe on the end of gauge wire that you think might be crushed, and touch the other end of the probe to some bare metal of the chassis (like where the negative battery strap is connected) and see if it beeps. If it does, your wire is shorted to ground. Only try this with the ignition OFF...
I’ll get a picture tomorrow I don’t think it has the setting though I’ve tried the setting I thought it was then every other setting to make sure with the black and red electrodes touching but no beep it looks like it has a little speaker on it though but it must be something else