The problem with the 'intelligent' PB 500 series batteries is that if a battery's charge gets too low, the internal microprocessor's memory cannot remember that it is intelligent. The trick is therefore to get enough charge into the battery for the microprocessor to take its thumb out of its mouth and remember its mission in life.
Put a battery most, but not all, of the way into the right-hand bay. Start up IBR. When the message about no battery in the bay appears, click the battery in fully and securely. If you are fortunate, the battery will be given an immediate precharge and verification. Proper charging can then begin. Try the process several times if you are not successful at first. Sometimes leaving the batteries in for several days with the charger attached will get enough charge into them to make the process above more likely to be successful.
If you can find a VST SmartCharger 500 (very scarce) and a copy of VST's app. EMMpathy, you may (just) be more successful. If nothing else, EMMpathy will present you with many data about just how many ways in which your battery is useless. If successful, it will install the Sleep Drain Bugfix, which does what its name suggests, and reveals one of the original faults with the batteries.
If a battery gets stinking hot during charge, it has too many internal short-circuits to be recovered. Chuck it, or re-cell it.
If none of the above is any good, there is re-celling, or in the ultimate, a new battery. Even (genuine) new batteries—upwards of USD50-80 each—are getting mighty scarce, albeit that they usually have ~40% more capacity (up to 2400mAh) than Apple's originals (1730mAh).
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By the way, 'Return it to Apple' means for disposal, not replacement.
