bicajos

You can install any of the patched firmware that is for the Axpert E 8 kW and the '28066 processor; at present, that's 92.06, 292.04, 392.04, and 272.66.
272.66 is based on the most recent factory firmware, but it only changes the two current compare statements. Present "best practice" seems to be to make a few more changes. So you may be better off with 92.06, unless you have a particularly high PV voltage, where 392.04 may be better (300 V minimum MPPT).
Just search for the appropriate numbers in this forum. I suggest that you start with 272.66.

@Peter Sam, I can confirm that the attached zip file contains main firmware for Axpert Max 1 7.2kW version 90.19, patched to avoid fault code 90, and with Georg's patches to avoid the worst of the "stuck at 90V" MPPT problem, with 120 V minimum MPPT voltage.
Assuming that you have a '2809 processor (probably with original firmware version 45.xx), this will solve your problem.
The fault code 90 is a brutal way to punish owners who buy cheap clones that use illegal copies of Voltronics' firmware, but it also catches out some legitimate Voltronic owners, who have an EEPROM glitch, or some other glitch. It only shows up after 60 days of runtime.
Edit: I'm not aware of any 7.2 kW models with the newer '28066 processor, but if you do happen to have one, then the new firmware will refuse to load, but you should not brick your inverter.

F90 is a " clone " detection but sometimes just a corrupt eeprom.
 
The firmware is based on 90.19 and shows this too.
It has F90 patch applied and mppt optimized like in my 8kw firmware ( these versions are nearly the same)

Hey guys
 
Thanks a million! I had the same experience with my 48V VMIII tonight. Updated main FW to 41.17 as per link in another thread on this forum, but display was not working after the update. Tried what jarjarbeens  said  with no success initially. I Just kept trying and trying and FINALLY got communication between the flashing tool and the inverter after about 20 attempts, trying different sequences.  When I powered the inverter on after the Main FW update, you could hear relays clicking with the fans on. The fans would go off after a few seconds, with some relay clicking that followed.
I followed what Jajarbeens posted above. The only thing I can add is that the power button needs to be IN (on) on the removable display. I got success when I pressed "Update MCU" on the flash tool about 3-4 seconds after I switched the AC power to the inverter on, just before the fans stopped. I figure that would before the normal starting 6 second countdown elapsed. Took about 20 seconds and then the flash started. Whole flash took 9 minutes and the display came on immediately after the flash completed. Restarted the inverter and confirmed that the Main FW was indeed 41.17, and the MCU version is 02.66 (that coulomb provided).
Once again thank you for all the generous information on this forum.