[snippage]
The service life of electrolytic capacitors is 17 years

Suspect capacitor was removed by hand. No change to beep codes,
'Continuous short beeps: Power error'. We are NOT going backwards! This
problem cap may imply other shorts on MOBO caps. Maybe time will tell;
'Aluminum Electrolytic Capacitor Self-healing'.

The top of this bad cap is hard to read because of damage. It appears to
have an industry standard purple crescent that implies polarity. From
little that is readable, I can infer it is a '470 uF 16 VDC Aluminum
Electrolytic Capacitor'. There is just enough lead wire left for
multimeter measurement. Resistance is polarity related. Conductivity
starts high then drops. Maybe this predicts behavior of other caps. Maybe
'Self-healing' will eventually work.

On the other hand, maybe pessimism is logical (Spock?). That would imply
replacement of all caps.

Comments?

The exposed socket shows no +5V, when 'Self-healing'. Maybe solder on
backside of MOBO is damaged?

My error. 'no +5V' was detected because it's not there. +5V is maintained to
mouse, keyboard and Ethernet(?) to support other methods of boot or reboot.
'Self-healing" only happens when board is powered up. Catch 22.