"I have to believe that inverters are like other modern electronics that it will be cheaper to buy a new one than getting it repaired"
A truism that promotes planet-raper resource depletion. Not a criticism of your response but a notation about general public consensus. I applaud the OP's attempt. I can only hope it works out.
If a law existed that I have mentioned numerous times before that insisted all expensive electrical and electronics be manufactured so a defect was repairable it would open up a whole new industry for the US, cause a natural correction with oriental chew & spit philosophy because of logistics
And finally such a mandate may end up being one of the most intelligent green proposals being offered.
But sadly no one is listening.