Not able to charge or run from MagSafe

A few months ago I was given an Early 2014 11 inch MacBook Air (A1465 1.4GHz i5) with no charger. I don’t know anything about the usage history of this machine prior to when it was given to me - everything that I know is from after the fact observation - but clearly the prior owner gave it away because it had some problems and she considered it not worth repairing. Right away, the first thing that I noticed was that the trackpad was badly cracked - it was held together and in place by some kind of clear plastic packing tape. Other than the trackpad, there were no external signs of physical problems or abuse.

Initially the machine didn’t seem to work at all and I only had MagSafe 1 chargers, so I borrowed a MagSafe 2 charger and after plugging it in the machine woke up and the battery started recharging - it must have gone into deep sleep from lack of battery power and was never actually shutdown.

The cracked trackpad seemed to function normally in all ways. The battery already had 674 charge cycles on it, but System Information and Coconut Battery both reported the battery's condition as Normal/Good. So I returned the borrowed MagSafe 2 charger, purchased a MagSafe 1 to MagSafe 2 adapter, and continued to evaluate the machine. I wiped the SSD and cloned an installation of MacOS El Capitan onto it from my primary MacBook Pro.

At first all of the MagSafe chargers that I used (and there were at least three of them) seemed to make a somewhat unreliable connection, though usually giving the normal green/amber lights at the appropriate times albeit maybe after some jiggling. But over time the MagSafe connections became less and less reliable until finally I wasn’t able to get a recharge going at all, no matter how many times I tried plugging/unplugging from the machine or jiggling the cord and connector. Through all of this, the machine worked fine under battery power while the battery charge lasted. One other note: all of these MagSafe 1 chargers, coupled with the MagSafe 1 to MagSafe 2 adapter, made secure and robust connection when connected to another MacBook that had a MagSafe 2 receptacle.

So I opened the machine and looked for signs of spill or other corrosion but didn’t observe any. Then, with the MagSafe disconnected, I disconnected the battery, reconnected the MagSafe and got a fairly consistent intermittent behavior of very brief green light, then no light, then very brief green light maybe switching very briefly to amber with the fan very briefly spinning up, then the fan stopped spinning and the amber light went off. This cycle seemed to repeat maybe several times per minute while the MagSafe was connected with the battery disconnected. Now, with the battery still disconnected, I am only getting intermittent (maybe every 20 seconds) very brief green light from the MagSafe, never the amber and never any fan. When I disconnect the MagSafe, reconnect the battery, and then reconnect the MagSafe I get nothing at all. Finally, last night I took the Air to a friend's house to try it with her MagSafe 2 charger (which works fine with her own MacBook) and got more of the same disappointing behavior from the Air.

From what I understand of all that I have read on iFixit and elsewhere, this seems to indicate a bad I/O board. So I plan to remove the board, inspect its underside for corrosion, and then probably order a replacement I/O board. But before I proceed any further, I am wondering if anyone here has any other suggestions or advice.

Thanks,

David