DO NOT USE FILE "Max 8K 91.04 old flasher.zip"!
If you have downloaded it, delete it! If you have attempted to use it, I'm so sorry, it is possible that you have bricked your machine. It seems that 91.04 main DSP firmware, which claimed to be an Axpert MAX I 8kW firmware, is actually for an Axpert MAX II Dual output 8kW, and uses a different command to initiate reflashing.
If this has happened (you attempted to load 91.04 and now you can't reflash the inverter with any other firmware), download the recovery zip file, and run the recovery reflash tool. This should replace the incompatible 91.04 firmware with the latest factory Axpert Max I firmware that I have, which is version 90.14 (note the unfortunate similarity in version numbers). Do not use this download for any other purpose. Sadly, I don't have an Axpert MAX, so I can't test this procedure. The recovery reflash tool is identical to the old reflash tool, except that the reflash start command has been overwritten with the one that the Max II dual output firmware will be expecting.
If there are further problems, please let me (Coulomb) know in the forums or by PM.
My sincere apologies for any owners that have been inconvenienced by this mistake.
================= Earlier comment: ===============================
Axpert MAX 8 kW main firmware version 91.04. Copied VP5K.INV from another archive as dsp.hex; that archive had a new reflash tool with a virus in it. This combination should work, but is untested. Use at your own risk. This version from about August 2022 is supposed to have fixed some long standing problems with PV charging, e.g. pulling the panels down to about 90V and very little current under some circumstances.
Do not use with any other model, but as usual an Axpert MAX 8 kW can be branded many different names.