Official 7" Touchscreen error, touch not functional

Other instructions are ambiguous. If you follow this blog post to the letter, playing close attention to all the photos there too (pay attention to the touchscreen flex photo, and examine the connector there too, in case it is opened or disconnected), it will work, provided that there is no fault with the display or software issues:  Raspberry Pi 7” Capacitive Touch Display: Assembly and Enclosure 

If you deviate from that, or go off and use some other power supply rather than the official one, then all bets are off.

Thank you for the response --  I did follow the instructions in the link to the letter... with the exception of soldering the power wires.  Other sources suggested use of pin 4 instead of pin2 for +5v but doesn't look like that matters and I've tried both. 

I went ahead and assembled the second Pi / Display set... and moved the SD card over to them ( I only have one to work with at the moment ).  Get the exact same result.  So hardware is identical to my initial case, and same exact OS. 

I've made no changes or additional installations on the OS... I did try a couple settings in /boot/config.txt which I've since removed.  I also did invert the display ( necessary ) in the Preferences... setting that back to Normal doesn't have any effect on the issue.  I've only changed one thing in any given experiment and then reverted.

So I'm concluding that the OS or supporting libraries the Pi folks currently have out there has a problem with the touchscreen somehow... being that both the 4B and the display have been around a while, doesn't seem like hardware itself would be at fault here.  But the problem renders the display half-useless.  

I'm expecting others are going to experience the same issue.  error -5 is above my pay grade, I've run out of ideas.

L

If you have a Pi 3B lying around, it would be worth trying that out too, just to narrow down further. The reason is, the 7" display was created in the era of Pi 3B, and Pi 4B is temperamental in terms of its power requirements, and the processor has significant differences that can break operation with software or drivers for the older Pi 3B.  I've encountered this so frequently with other hardware. that I automatically prefer to use a Pi 3B if I can help it, over a Pi 4B, if I'm interfacing to hardware and using software that is out of my control. 

This might not be a solution if you absolutely need the performance of a Pi 4 of course. It depends on your end use-case.

Anyway, since you have followed the blog post to the letter, I think you certainly have connected it correctly, and it may be worth raising the issue on the Pi forum (i.e. raspberrypi.com forum) too, for anyone familiar with the drivers for it to recall if anything has changed in this area with the latest OS.

I have a single 7" touchscreen but it is in use (with a Pi 3B running an older release), so I cannot test that unfortunately. The touch part is indeed useful to have (the display is quite low-res, so only really usable for appliance/kiosk-like tasks, not for general use as a computer display, so the touch interface is convenient).

If you have a Pi 3B lying around, it would be worth trying that out too, just to narrow down further. The reason is, the 7" display was created in the era of Pi 3B, and Pi 4B is temperamental in terms of its power requirements, and the processor has significant differences that can break operation with software or drivers for the older Pi 3B.  I've encountered this so frequently with other hardware. that I automatically prefer to use a Pi 3B if I can help it, over a Pi 4B, if I'm interfacing to hardware and using software that is out of my control. 

This might not be a solution if you absolutely need the performance of a Pi 4 of course. It depends on your end use-case.

Anyway, since you have followed the blog post to the letter, I think you certainly have connected it correctly, and it may be worth raising the issue on the Pi forum (i.e. raspberrypi.com forum) too, for anyone familiar with the drivers for it to recall if anything has changed in this area with the latest OS.

I have a single 7" touchscreen but it is in use (with a Pi 3B running an older release), so I cannot test that unfortunately. The touch part is indeed useful to have (the display is quite low-res, so only really usable for appliance/kiosk-like tasks, not for general use as a computer display, so the touch interface is convenient).