Sounds like a deep discharge issue, related to the battery metering being out of sync with the actual battery SOC and capacity. Leave it on the charger for however long it takes until it begins actually charging. Until it does, you'll see the white light. Then out of nowhere, you'll hear it beep and begin charging. It could take a day or more until it very slowly trickle charges the battery enough to jumpstart the full battery charging and monitoring circuit.
Once it fully charges to 100%, remove it from the charger, power it up and use it normally until when it notifies you to connect to a charger. At that point, or as soon as possible thereafter power the phone off completely and then place it on charge again and allow it to charge to 100%.
Once charging has completed the second time it should be ready to go and you shouldn't have any problems with it again. Just make sure to never discharge much below 15% before placing it back on charge, and every so often, about every two months or so power it off completely and charge to 100% while powered off. Do this and you shouldn't have any problems going forward.