HP97: Who was the killer (resistor or transistor)?

[Hans-Peter]

I have a 97 for repair, which at first glance had no signs of error (except Reader and Printer). When I opened I was greeted with plastic splinters.
Diagnostic SD-15B ended with code 45.00
The resistor R4 I could simply replace, over a replacement for the PNP transistor Q1 1853-0395 I found nothing. So I took the universe type 2N3906. Now the Diagnostic also runs through and brings the value 10000000.00.
   
Now is the question of the perpetrator? Are there other victims?

Hans-Peter