2011 Nissan Leaf OBC circuit issue, need advice

Similar to many other early leaf owners, my leaf can take Chademo DC charge, but the AC charge always stops after blinked and beeped for a couple of seconds.

By following this thread and many other messages on this site, I took out the onboard charger and did a diagnosis.
https://www.speakev.com/threads/a-guide-to-changing-the-onboard-charger-on-the-nissan-leaf.160015/

I found a burnt capacitor connection on the bottom layer PCB.

The PCB, the lower left corner capacitor has a burnt connection:


The back of the PCB, the burnt connection looks obvious:


Close look of the 310v 2.2uF capacitor has the burnt connection:


Please give me some advices on:
1) What are the three black small button shape components that are adjacent to this bad capacitor?

2) Can I add (solder) a capacitor on the back of the PCB instead of removing the original one?

3) If I have to remove the capacitor and replaced it with a new one, what is the best procedure? Should I use a heat gun to remove the gel, then use solder iron to remove the capacitor? The three adjacent black button shape components seems have to be replaced also if a heat gun were used.

Those black lollipops are transient surge suppressors, Panasonic 20mm ZNR series. Check to see if they are shorted or low resistance. in the 3rd picture they appear to have some arcing or dust on the top side. Maybe you had some lightning and the ZNRs popped.

The black potting material is very soft and rubbery and easy to remove with a wooden spudger. i use a bamboo chop stick and sharpen one end in a pencil sharpener and use a knife to whittle a flat blade on the other end. Don't use a heat gun, it is not necessary and likely make a mess.

The black mark on the AC input filter capacitor solder joint looks like an arcing event occurred. Does the cap measure okay or is it shorted. Best bet is to remove the potting from above and then desolder the cap from below.

Inspect the 3 white ceramic resistors and the relay and caps over in the central section, that is all in the AC input circuit also.

Hard to believe that the fuses didn't blow, but there is something open circuit that is causing the charging session to not start. F101, F103 and i see a little brown F104 over on the bottom right side in your picture.

I dug out the 2.2uF capacitor, one pin is burnt off from the capacitor. The plastic around the pin had been melt and deformed. The capacitor should be the disconnection point.

I checked F101, F102, F103, F104, they all have continuity.

I will order a capacitor and try to solder it on the PCB.

Are any of the leads available to measure if the capacitor is shorted? That is an AC filter cap between the two mains input wires marked as L and N, for Line and Neutral on 120vac, or L1 and L2 for 240vac.

The cap is normally an "open" so i don't think that is your only problem unless the cap was somewhat shorted as in a low-impedance short circuit.

Once you have the part you could take it to an electronics or cell phone repair shop and get them to solder it, if you are not comfortable with soldering.

[edit] AC voltage will jump across a small gap (arcing) which will erode the junction over time. Maybe the lead wire on the capacitor was bent, stretched, cracked or broken right at the solder joint on the top side, and over time this high resistance junction was eroded away due to arcing.

After changed the problematic 2.2uF cap, the OBC still fail in the same way as before.
Sounds like a multiple points failure. Don't want to spend extra efforts on debugging.