[Help] 1st soldering job gone wrong, can it be salvaged?

[kikomir]

Greetings everyone. Long time lurker around here but only now posting. I tried doing a custom board by soldering but I messed up the soldering and am now asking for help to diagnose the problem and fix it if possible (waiting on a new PCB to be shipped would again take a very long time, months even). The PCB is an XD60 rev.3.

The problem is on one column I get 2 keys registered per 1 key pressed:

7 and 8 registered when pressing 7
U and I registered when pressing U
J and K registered when pressing J
N and M registered when pressing N

All are on the same column - diode/resistor numbers 36, 37, 38 and 39. I would be very grateful if someone can help me out how to diagnose and fix this problem as I am lost right now. Some photos on the following link but I can snap more if needed. 36, 37, 38 and 39 are extra messy because I tried desoldering them one by one to find out where the problem lies. There are washers under all stabilizer screws and the soldering iron had a temperature of around 300-350. The PCB itself was tested before soldering and it worked flawlessly.

https://imgur.com/a/2yjs3bp

Any help is greatly appreciated.

EDIT: the problem was caused actually by the firmware so by using QMK the problem is solved. Leaving this for future reference in case other people run into the same issue. USE ONLY QMK!

[yui]

my guess would be that you overheated a diode that is now shorting, or that your flux is conductive and shorting with something, at 1st glance i see nothing wrong with your solderling

[kikomir]

I cleaned the PCB with isopropyl alcohol to clean the flux but it didn't help. What can be done about a overheated diode?

[yui]

you can test them with a multimeter without one you are kinda out of luck, you need to test in diode tester mode if one way they have a low-ish reading and the other a very high (should overload) reading, if so they are ok, if it is 0 or close both way then it is dead
Although yesterday i said that because i saw nothing wrong with your soldering, but it make little sense that it would be that given the symptoms... to me it screams that you shorted 2 rows together but i do not see where...

[leetuser]

Nevermind