Should I have immediately gone for a drive

Yes. When cars sit for awhile, just idling them isn't enough. Starting the car is the drain on the battery, as once it's started you can actually take the battery out of the car with it continuing to run. When you started it (after sitting for awhile) it needs to drive, preferably on a highway where you can get the rpm up to around 2000 for 7-10 minutes.

Sorry this is hitting you hard economically. Have you tried applying for unemployment? The feds relaxed the guidelines to include self employed/gig workers so you should qualify (unless you have that libertarian heart and it was under the table ).

Realize that and be KIND

Words that should be embraced at all times.