Macbook Air 2019 will not boot from USB or complete Internet Recovery, Exhausted options
Call Apple or chat online with service would be my next step. Ask for a mail in repair if available and convenient. #3 is really unlikely to be anything easy if you have charged it for 2 to 4 hours.
Flat rate repairs for these are quite reasonable amd it would cover things like battery and or cpu board. Possibly under warranty or a program, worse case you get a quote for a professional battery repair.
A totally flat battery can drag the whole controller and board down. Hard to say until it’s in the shop with known good parts to test things out internally.