MiniDisc repair - Kenwood DMC-T55 - rookie mistake...

Well.

This one was supposed to be a video! Unfortunately, mistakes were made... 

A recent Buyee find: A beautiful orange Kenwood DMC-T55 with remote (you NEED these with Kenwoods since they aren't cross-compatible between S/T/V models...) that wasn't confirmed to work.

It was cheap enough that I gave into temptation!

Upon arrival, I confirmed it was indeed in beautiful condition, but wouldn't power on with a gumstick. 

The battery terminals that I could see were pretty clean (inside the battery door, negative terminal deeper inside), so it was time to open it up.

I started the video and started opening the back and at some point got frustrated with the lighting and focus so paused/unpaused a few times while I adjusted.

Unfortunately, when I continued I mistakenly paused the recording instead of unpausing it... 

So, I'll just quickly recount the steps here with what's left of the video.

Let's open it up - just the bottom panel was needed and you don't need to remove the battery door. If you look closely, you'll see the bottom shell can be removed without messing with it.

First, the top screws by the control buttons

Then, one screw by the eject button and headphone jack

Two by the battery door

And two at the bottom panel

Pay special attention to the two blue arrows - they're pointing out two black rings that help line up the charging/speaker dock. After you remove the back case, they will fall out and can be a bit tricky to get back in... 

OK once I was in, I confirmed that the battery terminals were indeed clean, but the culprit this time was right at the battery door hinge. See this capture from the video (after it was already cleaned):

That red circle shows how the metal part in the battery door connects back to the main board to complete the power circuit. In this case, it was completely covered in green corrosion residue! I'm guessing whoever sold this cleaned the battery door, couldn't get it working, then sold it as junk.

All I had to do was the usual: Cotton swabs, some vinegar, clean with isopropyl alcohol. This was a quick 60-second fix!

I tested before I re-attached the bottom by sliding in a gumstick.

Reassembling this is a bit tricky because of those little rings I pointed out earlier. There's also a "hold" switch to watch out for. Since the switch on the bottom case is just loose with no friction to keep it in place, make sure it's in the "down" position if you're holding it upright. Then look inside the player to make sure the physical switch is in the same position.

This was the easiest way for me to get it back together without the plastic rings falling out. Gently put them into place with tweezers and hold everything so they will be facing "down". Gravity will keep them in place while you attempt to sandwich everything back together.

Start at the headphone/remote jack side and put that part together first, then gently push it together.

If they slide too far out, you'll want to start over. If they're nearby and you can still see them, just use some tweezers to get them back into place before screwing the bottom case on.

Screw the bottom half on, that's it! I had a working Kenwood DMC-T55 in great shape with just about 60 seconds of cleaning.