Commodore 64 showing a black screen, can I fix it?

I was recently lucky to pick up this Commodore 64 from Woz who had offered it on RMCs discord for the low price of postage only. What's the catch? Well it doesn't work, its displaying a black screen only so lets try and figure out why? Will it just be the PLA (a common failure point for a black screen) or will it be something else?

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Music - Cathode Ray Gun by @Momentvm

Chapters
00:00 Intro
00:20 Looking around the system
02:39 What's the symptoms
08:47 It has to be the PLA
10:42 Testing the VIC
11:32 Anything getting hot
12:45 Probing the MOS logic
15:23 Why is U15 not being enabled?
20:15 Replacing U15
21:06 Diagnostics
22:32 More problems?
23:07 Refinishing the edge connectors
24:44 Testing again
25:25 4066
26:22 Keyboard test
27:19 Loading a game
29:08 Conclusion and credits