Can;t update Windows 11 to 25H2 after Win 11 install on unsupported machine.

Few months back I used Flyby to update my non supported PC to windows 11. My processor was the problem being not compat with windows 11. All went well. Now the 25H2 update is being refused by windows update saying my processor is not compatible. Have tried the new FlyOOBE app for this work around but will not install. Any thoughts on this will be helpful. Thanks in advance. Ohh...BTW...I updated a 15 year old PC to windows 11 with latest ISO 25H2 and guess what. Loaded everything all including 25H2 support. I can't reload the new ISO on the other PC as it loads it all until final set up and says can't install because of ...The installaation failed in the First_BOOT phase with an error during BEGIN_FIRST_BOOT operation.