Updating a file that feels cursed on a spiritual level

I'm an epileptic currently not in employment due to repeated seizures at my last job.

Been trying to get some side gigs here and there, reached out to a friend from work and she connected me this old guy who sent this gig to update an Excel file.

I'm very much grateful to her but I won't wish this on my worst enemy.

It's a 6 year old file with undocumented revisions in the triple digits.

It contains random cells that only display input or formula instead of calculating. The whole thing is just merged cells where Excel's copy paste logic fails. I need to copy it one row at a time.

Some genius even put a picture that displays just white over it, so few cells aren't even joint cells.

Must have been exercising his free will.

The header situation is also cursed.

The table has multi-row headers, and then halfway down the sheet the header row randomly appears again for no reason. Some rows are hidden, some are grouped, and occasionally there's a blank row right in the middle of the data that breaks sorting.

I'll still try my best to get it done asap but damn this is one cursed file.