Power Cable and Battery

I have been trying to find answers for this for the last few weeks.

I have a 2017 MacBook Air with the I7 processor. I’m on my second battery and second charger cord with this computer.

The first battery died after only about 500 cycles. The new battery had 289 cycles and the full charge capacity is (mAh): 6543.

My first charger started to brown close to the MagSafe Connector. I have also noticed that when the cord gets pretty hot when I’m charging the computer. I can hold the MagSafe but it is on the verge of being too hot.

I have also noticed that the left corner computer gets warm while in use. I have taken it apart and dusted it. I have also upgraded the thermal paste. I’m wondering if it is my I/O board that is the culprit.

I do need to add, I have also reset the SMC.