OSError: [Errno 5] Input/output error

Two weeks ago, after a previous issue with the library was resolved, everything was working perfectly via I2C. I started with the example code and then moved on to writing my own, using both the display (connected via Stemma QT to the “Adafruit I2C Stemma QT Rotary Encoder Breakout with Encoder - STEMMA QT / Qwiic”) and a rotary encoder. Both devices worked simultaneously without any problems. However, recently, without making any changes to my Raspberry Pi 3B+ setup or wiring, I started getting the following error, even when using the example code:
OSError: [Errno 5] Input/output error.

This error only occurs when trying to use the display. The rotary encoder works fine, and both the encoder and the display are detected via i2cdetect -y 1. Here’s what I’ve tried so far:

- Connected the display directly to the Raspberry Pi via I2C (without going through the rotary encoder)

- Tested a second display of the same model

- Changed baudrates in case the issue was with communication speed

Despite all of this, the error persists.

I also switched to SPI as an alternative, and it worked at first, but the issue returned after about a day. While SPI does not raise an error in the terminal, the display remains black.

Given that the display is consistently detected by i2cdetect, and the rotary encoder works without issue, I’m not sure how to proceed. Any help or insights would be greatly appreciated.

Start by reproducing the error with the library's example code on the Raspberry Pi 3B+ over I2C, then compare the display's behavior with the rotary encoder and the results from i2cdetect -y 1. Check whether the same failure occurs with a direct connection, a second display, changed baudrates, and SPI; done means the display operates reliably without the OSError or a black screen.

Written by the indexing model from the issue text.