I have to agree with @sterretje here - the DS3231 has an isolated battery input which is specifically designed to keep the internal clock (not the I/O pins) alive when Vcc is gone. If you turn that diode around, your battery will be trying to drive Vcc (at around 2.3ish volts) and potentially an entire system connected to it (not just the power LED!). The resistor/diode combination really just looks like an extremely badly-designed charging circuit, or a circuit designed to charge a supercap (which should actually work quite well). So either use a supercap (would be nice if a supercap was available in a CR2032 form factor!) or disconnect that circuit to avoid a nasty fire/explosion.
2 Likes