I have 12 volts going in to inverter but nothing coming out the 230v side no led lights on. Is there a reset or an internal fuse?
first measure the battery voltage at the inverter terminals.
second is to make sure the inverter is switched on with the small control switch.
If both of these are good, then try using a Mk3 device to communicate with the inverter, if this fails then the inverter is faulty. If you get communications this can tell you more about the problem.
Set up at 250-400A fuse for DC wiring to Multiplus.
Measure 230v out at the multiplus with inverter on.
Shorepower is passthru, so measure DC at terminals on MP first.