Any idea what’s causing this to the battery?

Thanks.  This is a foldable bike so the battery stays inside.  I have no idea how it got so dirty so fast.  It wasn’t like this last time I broke it apart.  I’m going to use some electrical cleaner on the prongs, hopefully it fixes it. 

Thank you very much!!! Going to do this today after work 

I cleaned it today, I’m going to wait until the morning to reconnect the battery.  Hopefully it works!  
 

This is what I used 

The fuckers at Home Depot told me that WS 40 was safe for electrical outlets, just be gentle.  
they probably had no idea what they were talking about.  The other stuff like degreaser I got to clean the bike.  I didn’t put that in electrical outlet.  I also used the duster air cleaner afterwards so hopefully nothing harmful was left behind.  The connections actually cleaned pretty well.

I went to put the battery back in today and ride and it turns out that dirty connection isn’t the issue!  I am so damn upset.  I used to be able to take apart dirt bikes, now 20 years later I can barely install a brake line.  Stuff frustrates me so dang easily and I get so much conflicting info from YouTube vids.

long story short (thanks for reading so far) my bike turns on and works fine when I hold the battery in place, or LEAN it to the right side.  Any time the bike is level or leans towards the left (kickstand side) it shuts off completely.

I have have someone tell me they think a wire came loose because my bike is foldable, they told me to check the back of the CONTROLLER.  I have only folded it and put it in my car one time and it worked fine for a few rides after, but ever since I folded it something happened.  I have a friend that has the same bike as me but he’s not that knowledgeable, he takes it to the shop, I cannot afford to, but I might have to.  

Ok sorry for not reporting back sooner. I got a nasty sickness this week!  One of the worst colds / fevers iver ever had.  
 

but the good news is…  I’ve been able to FIX my problem and the bike rides perfect! 

praying it stays working well.  I will explain exactly what I did, what the problem. Was, I will show photos, but basically what it came down to was my bike is foldable and the wires always get pinched and pulled .  I’m have since read a lot of people saying with their foldable e bikes they have connection and controller issues because when they fold the bike the cords stretch inappropriately.  Sucks to read this because I have a car and loved fitting in in my trunk.  I’m really hesitant now .  

  So I checked the controller for loose cords, everything looked good, so I knew it wasn’t this issue… 

To add to above 

So this is what actually worked!!! 
 

so I removed the BATTERY itself a ton and cleaned it and but I never removed the rack it sits on and has 3 wires under it! 

 I saw the slide the battery sits on, it’s only had 3 bolts holding it in.. there are 3 wires that run underneath it.  What I did was reconfigure those wires so the battery would be tight and lean the way I wanted it.  I ended up not being able to attach the battery to the controller because there was a fat cord under the slide , my attempt to raise the battery made the connection uneven.  
 

so I put the rack back in, and I configure the wires basically the same way they were thinking this isn’t going ti fix it.  And waaaalahhhh !  The battery fit in tight and the bike works better than it did before!  
 

these are photos on the slide I’m talking about, 

Another update.  Almost all these problems come from the foldable feature.  I just snapped another rear brake line.  Damn foldable feature causes so many issues.    I have a small car with it fits in the trunk, but I’m thinking of buying a bike rack on the back of my car.