To remove the pin cap, just pull it straight up, either with fingers or plastic extractor tool.  Have you seen the pin cap located between CMOS battery and RAM slots.  Usually, there is a printed instruction on motherboard, showing you which pins for which function.  Just short CMOS pin for 5 seconds, or leave battery out for 5 minutes.  ESCD data (BIOS) will be reset to default. Point is, learning and practicing to troubleshoot your machine which still has a high chance for revival.  On a side note, be certain to use correct AC adapter intended for the machine to provide sufficient power.
I have a 4 yo Inspiron 24 Desktop AIO that was working fine until the RTC kept kicking off and beeping (needed to reset on BIOS page) I got the battery and replaced it inside but now the unit won't turn on at all.  The power supply is working (green light) but when I push the power button it just blinks once (amber light) and goes off.. nothing else happens.  I tried to discharge by holding the power button and redoing the power supply but nothing... I can't find anywhere what 1 blink light means.  Any help please?  Thanks
Inspiron 24 AIO won't turn on