Cannot launch MSFS

I was running flight sim on Steam , loaded directly to my internal hard drive and it was ok , I wanted to move the files to my external hard drive and i uninstalled on steam , created a Steam folder on my external drive and reinstalled the game then .
Now i canot launch the game , it starts to load then crashes out , steam shows game as running?? I assume that a file is left from the C drive install ,and that is crashing game out , have uninstalled cache and everything else I can find but no luck , also reinstalled on C drive but exactly the same issue now , I am totally at a loss what do do , hopefully someone has had a similar issue and can help me !

Check in C:\Users\InsertYourProfileNameHere\AppData\Roaming and look for an MSFS folder. Path may not be exact as I going from memory and you may need to look around. If there is one, blow it away.

I did as asked and there was an empty folder FS folder there , deleted this and tried to run game but same issue , hit play in steam , starts launching , initail black screen for about 1 second , the crashes back to desktop , also steam shows as running briefly before the play button comes on again