As the title says, I have the same problem. Won't complete charge, discharges in seconds. I have it constantly plugged into an external power bank, but even now it has started randomly shutting down. It's gotten to the point where it won't hold a charge *at all*. Have tried every suggested diagnostic/fix. NOTHING WORKS.
If I knew how, I'd replace the battery myself.
Bought from Amazon on April 29, 2020