[FS2020 does not boot up after installation of RDPreset's LIRN]

Hi.
It sorted itself out after I switched the PC off for ten minutes and tried it again. Never saw such a thing before. No night lighting at LIRN was a surprise.
Anyway.... to answer your questions:
Windows  10 to the latest update state.
Community folder size 238 gigabytes.
Latest sim update 10 installed 1.26.5.0 (no beta)
 
No... not rolled back to SU9

[FS2020 does not boot up after installation of RDPreset's LIRN]

My sim was working fine this morning. I shut down FS2020 to Desktop..... I saw a new Naples LIRN from RDPresets, and purchased it.  After downloading the installation zip file, I unpacked it, and ran the installation as Administrator, inputting Email address and Keycode when prompted. The installation seemed to go without any problems, and I restarted FS2020.
Sadly, it would not boot to the pre-flight screen. I uninstalled LIRN from the Apps, but the sim still refused to boot into the pre-flight screen. I removed everything  from my Community folder, and deleted my FS2020 Cache,  but it would still not boot. I unistalled FS2020 from steam, and re-installed it. It booted to the pre-flight screen in Safe mode. I rebooted it in normal mode successfully. I replaced everything back  into my community folder, so the only thing not there was RDpreset's LIRN. The sim booted normally, and I even loaded and launched into EGLL successfully.
I shut down the sim, and re-installed RDpreset's LIRN. Once again, it failed to boot to the pre-flight screen in both normal and safe modes. The blue loading indicator reaches the far right but does nothing else, so I am permanently on the loading screen
Please advise.