Fescue is different that St Aug. St Aug is wider bladed. Several types of fescues. Lots are blends of different grass seeds like Kentucky Blue Grass and so on.
Try another weed ID ap.
Look at Google images for Mondo and Lawngrass. See what you think.
Take that sprig you plucked to a plant nursery. Get their opinion.
Chickanic on youtube found that canned fuel I think she said was stale or full of water. There was something wrong with it. Maybe it was old age? Anyway she said not to use it. No telling how many years it has been sitting on the shelves. Not many people buy it.
What RPM do you mow at? Do you ever idle it down?????????
All those cranking attempts will drain the battery. No wonder it didn't start back up.
It takes several (15) minutes at MAX revs to "nearly" charge a battery back up. Mowers do not have large alternators to immediately top the battery...
Solder and marine grade heat shrink is a nice way to terminate properly. Marine shrink has a glue inside that ooozes out and seals the bond from the atmosphere.
Good tips above.
Pull the fuel hose off AT the carb inlet. Drain into a glass jar or can. Look for water at the bottom. Specifically look for a healthy flow out of the hose. Do this till the tank is dry. If it has good flow for a bit then crawls, you have a tank vent issue. Good flow draining...
I would prep the seat pan. Sand off all the old adhesive and paint. Use rough paper to allow the adhesive to get into the metal and stick. It's all about the prep work.