If you have an HP 48SX or 48GX that won't turn on, check to see if you have this common problem:

• https://www.reddit.com/r/hpcalc/comments/hwsh6k/hp_48gx_calculator_keyboard_issue/
• https://groups.google.com/g/comp.sys.hp48/c/RvfzLHeqZ1E
• https://youtube.com/shorts/4SMhyDHLXeM?si=iQAK3yX7rZ4HvCz1
• https://youtu.be/_Jcwjtryf4Y?si=JOliJqU0oaud-CCc

In short, you have to press on the bezel underneath the screen while pressing ON to get it to turn on. I looked into what it would take for a more permanent fix, and it requires a full disassembly: 

• https://youtu.be/3roTLMhoBOM?si=mlGYxN8ON4TKub-t
• https://youtu.be/ZrVQ8SyQ4EU?si=u-P5sK0m3uJ1mdRU

Eventually, I needed to press on the bezel not just to turn the calculator on/off, but to use the 6 buttons on the bottom right (+ - * / etc.), and those are pretty important buttons, and it was getting annoying. This print underneath a rubber band does the trick for me. Try to line up the raised, wedge-shaped bottom in between the B and C keys on the top of the keyboard. You can see a black arrow in marker on the bezel in my photos.

I hope you find this useful. My HP 48GX is 30 years old this month, and it's one of my favorite devices.