So, this inverter had a minor oops, and the smoke came out of the main controller. Still sort of works, in that it does not go bang on power up, ad the start up circuitry and the isolated power supplies still operate, so there is a 14V rail to drive the input and output circuitry, but there is no display scanning or drive.
Not surprising, seeing as the display is blown totally, both the led displays themselves, and the drive transistors. Main processor as well has a hole blown in it exposing part of the die and the remains of bond wires in the pit. Main power block and driver is probably fine, but I need a new drive board and display. Otherwise it is just scrap metal and eWaste.