I have two of these in service now for about 5 years.
This failure was my bad, I tried switching from inverter to 120v and back with a D. P. D. T. relay.
I did not take into account that the compressor would be out of phase with the inverter some times.
POOF!! Now I have a 5 min time delay for switching back and forth from 120 to inverter, all is well.
I rewired the Fet drivers so as not to have to work with the Surface mounted fleas and crap.
When the Fet's shorted they also burned off some of the runs to the cheep SMCs.
so far its been on line now for two days at 400 watts.
Seems to be working ok its 100 degs. and the fans are only running about 30 percent of the time.
Will shoot for 1000w later during Air Conditioning season. Fingers Xed.
The most I ever run is 1200w in the winter when its cooler, due to the false Bloated advertising.

Major Modifications:
N3, N4, N5, N10, N8, N7, N21, N20 and associated circuit placed on 4 small Driver Boards Attached to the MOS Fet Heatsinks.
4 extra Fets added. Replaced all with IRFB7437pbf Fets. On resistance .0015 ohm. Originals were MXP400BTS .003 ohm.
Disabled all the Surface Mounted Flee and Tick circuitry by cutting runs on the board. Added Terminal Strip.
Hard wired drivers to terminal strip after installing them back on the board.

Note: Disclaimer, this is a hobby. Nothing is really worth fixing any more.
The inverter is only $140 It cost $40 for parts and 20 Hours Labor. At ($50/Hr) Cheep $1000 :-(

 

Update! July 18 2017
The inverter is now running a 6000 btu Air Conditioner with many start stop cycles due to the MonSoon's.
All is well should be better than the original cheepo SMC's , will keep all posted if it blows up
It is also now fixable without the SMC's.
Love fixing this stuff. Held breath when starting the AirConditioner for the first time though!

 

Update! Feb 18 2018 The above repair is still in operation.
A new problem is starting at the 5 to 6 year mark though.
All the main capacitors in one of the units have failed.
See this interesting article Capacitor_plague
Just ordered enough caps to replace them in the 8 Units on line.

 

This really help me out my E 16 blew up and I couldn't figure out what size it is and it's 100 µF at 16 V thanks to your posting here. I'm super grateful for your dedication to helping others your angel without wings.