I would invest in a temp gun and follow these limits:

Battery < 120°F
ESC < 140°F
Motor < 160°F

Some manufacturers may list higher temps than these limits, but that's just to protect them from not failing before the warranty expires, typically 90 days for most brands of electronics.

Sounds to me like you pushed the limit and got your money's worth after the warranty expired... I would go up to higher rated ESC and check temps regularly.

If it were me, I'd upgrade to this ESC here if I was gonna run on 3S, this ESC will stand the test of time:
https://www.hobbywingdirect.com/prod...nt=20187925828

If I was short on cash, I've had luck with this ESC too, but you get what you pay for, I've had to replace the switch on these ESC's, but they typically last 1-2 years before they have failed on me:
https://hobbyking.com/en_us/hobbykin...e-version.html