harry201204

@Elee09 Unfortunately I wasn't able to succeed in rolling the firmware back, so I'm stuck on the current version.

I tried using the latest downgrade tool that @Dejan Fehirov linked me but sadly that didn't help, I still got the same error message and wasn't able to complete the downgrade. If anyone has any more ideas on how to fix the issue I'd be really appreciative though!

I wasn't able to get @SIMON's method to work unfortunately, but I followed @smx's tutorial to roll back the firmware for my LG 55UF850V from 4.05.60 to 04.00.90 and that worked, up until the point where I tried to run the update on the TV. The TV was able to find the available update (coming up as 04.05.61 on the tv), however when I clicked "update now" it said update failed immediately, giving the error message "Update failed because SW version is lower than TV SW version". Has anyone else had this issue and been able to fix it? I think perhaps it might have been because I was trying to update using the usb version of the .epk file (that's the only file I could seem to download on the lg support website) rather than the nsu version, but I can't seem to figure out where to download the nsu versions. 

Is anyone able to advise on how I could fix this issue? Any help is greatly appreciated because my TV is running very slowly on its current firmware version!