2004 Camry alternator vs computer vs?

I have 2004 Toy Camry XLE 224K hiway miles. Battery indicator started blinking but alternator/battery checked out ok. Mechanic said he wasn’t sure, keep log and bring it back. 2 days later, all panel indicators came on, radio dimmed and I limped home - wouldn’t start back up. Is this the alternator, a computer prob or electrical? HELP! I want to be able to have discussion w/shop when I haul it in. Thanks - by the way, I love my car/want to fix it.

A common symptom of alternator brushes gone bad. The alternator begin to fail intermittently and will make the alternator light go on and off as the worn brushes make and loose contact. It will test OK if the brushes are in contact at the time of the test, but will lose contact again until they lose contact for good.

Replacing the alternator is the best and quickest way to fix it.

I thought it was the alternator and actually made the appt to have it replaced but the mechanic was reluctant - now I’ll insist on it - or take to another mechanic. Thanks