Fluke 8808A/Tektronix DMM4020 - Troubleshooting the Fleet

[Eiskalt_NX]

I'm a student technician in my University's electronics shop. ~700 units of test equipment in the labs and in storage. Mainly HP & Co., along with some Tektronix; spans early 90s to about 2019. Current task is working through ten Tektronix DMM 4020 aka Fluke 8805A. I have been unable to find a proper service manual for either of these models. I've read through the user and calibration manuals, plus some online content, but nothing in terms of troubleshooting or schematics so far.

I did contact Fluke but they just sent me the calibration manual. Waiting to hear about anything else.

The first one I have is unresponsive to power-on. Currently checking the the combined power inlet/fuse holder/input voltage selector assembly and transformer.
Others have display issues or are unresponsive to measurements.

Main PCB: 8808A-RNET-3001 REV 003 [Date: 1616] [Copyright 2013]

Resources I've found so far:
https://www.avrfreaks.net/s/topic/a5C3l000000UUWZEA4/t131129
https://us.flukecal.com/literature/product-manuals/8808a-calibration
https://www.eevblog.com/forum/repair/fluke-8808a-won_t-auto-range/msg838660/#msg838660
https://www.eevblog.com/forum/testgear/fluke-8808a-question/
https://community.element14.com/products/roadtest/rv/roadtest_reviews/1202/review_of_tektronix
https://elektrotanya.com/fluke_8808a_calibration_manual.pdf/download.html
https://www.eevblog.com/forum/projects/is-this-capacitor-deformed/msg740503/#msg740503
https://www.eevblog.com/forum/blog/eevblog-427-hp-3478a-multimeter-teardown/msg194441/#msg194441

Adjacent Information:
https://xdevs.com/fix/f8846a/