Low battery and will not charge - iRiver B30 (8 GB) Digital Media Player

During charging, RECHARGE indicator turns red, when the indicator is fashing,

that means battery is almost full and turns OFF when fully charged.

There's some Manual sites here...
https://duckduckgo.com/?t=ffab&q=PWMA1050BT+low+battery+blinking+red&atb=v159-1&ia=web

The Rii i8 is a wireless keyboard with a built-in touchpad and backlit keys. The yellow flashing light on the Rii i8 keyboard indicates that the battery is low and needs to be charged.
When the battery is low, the yellow light will start flashing, indicating that the keyboard is in low-power mode. To charge the keyboard, plug it into a USB port using the included charging cable. The yellow light will turn off once the battery is fully charged.
It's important to keep the keyboard charged to ensure that it functions properly. If the battery is too low, the keyboard may stop working or the keys may become unresponsive. It's a good idea to charge the keyboard overnight or when it's not in use to ensure that the battery is fully charged when you need to use it.

It depends on the level of discharge of the battery and the rate of amperage charge generated by the charger. If possible check the fluid level (acid/water) in the battery. If it is too low the battery will not accept a charge. If you add water (distilled) to the battery you charge at a low amperage charge rate if possible. A fully discharged battery may take 12 - 24 hours to reach full charge.

Either not charging, battery not holding a charge low electrolyte (or just knackered), Needs charging then a voltage drop test.

A Battery Tender will not charge a battery. They will maintain a "Charged" battery. Typically, if you put it on a low battery it will stay low of charge. Try cleaning the battery terminals and charge the battery, then turn the Battery Tender on.

If the cell phone battery is more than 3 - 4 years old then the battery could be worn out.Rechargeable batteries have a finite number of charge and discharge cycles andwill lose their charge capacity over time, i.e. won't charge to 100% andgradually the charge reduces until the battery won't charge up at all. OR Thebattery shows a 100% charge but when the adapter is disconnected the batterydrops off to zero capacity in a very short time. If the battery drops to anunacceptable charge level then the battery needs to be replaced.

It can be so simple that the charging circuit protects itself by not charging when the cell voltage is so low.
In some cases, you can gently charge the battery with a older type charger, to bring up the voltage so much that the charging circuit accepts the battery and starts its charging.

A simple reboot of the phone can resolve this problem. Failing that a complete resync with iTunes does the trick too.

y hp6365 keeps telling me that i my backup battery is low..i keep charging my phone but the only the main battery is charging..how do i charge or change the backup battery?

Must recharge every day by replugging into your computer