End Of The Line For My Powerbank?

Weirdest thing just happened.  I have two power banks (is "powerbank" one word or two?), and that gives me the flexibility to keep my phone constantly charged whenever one of them needs to be recharged itself.  That just happened tonight with my older power bank, and so I switched it out with my newer one and plugged it in.

I just checked on it.  There are four indicator lights on this powerbank, small blue dots, each of which blink as it's being recharged.  And it is on two dots, and two dots only.  There was no blinking third dot.  I touched the plug; it was hot, which means to me that it's still charging.  But there is no outward sign that this power bank is indeed charging.  I usually wait until my powerbank is pretty much out of energy before switching it out, but I don't wait until it's completely empty.  But it was empty this time, and actually for the first time I can ever remember.  I just thought I waited too long.  This instead might be a sign it's gotten so old it can't recharge anymore.

I'm not too keen on buying something I didn't think I would need to replace in quite a while, but depending on whether it can charge fully and how well it can recharge my phone, I might have to shell out more money for a new backup power bank.  Great.