Suddenly, the DisplayPort (DP) port on my JN-V315UHDR, which I was using as an external display for my MacbookPro, stopped working.
After various trial and error, I solved the problem, and I’m going to record the details.

Connection environment

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| - | - | - |
| Terminal | M1 Macbook Pro 14-inch (A2442)
| Display : JAPANNEXT JN-V315UHDR
| DisplayPort
| DisplayPort | Usage cable | BENFEI USB-C - DisplayPort cable, 0.9m USB Type-C - DisplayPort cable [Thunderbolt 3 compliant] |
| Frequency of use | Almost every day all the time

Investigated and resolved

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official support page provides the investigation method, so follow the instructions. 1.

  1. check if the display is turned on -> Yes
    Is the display connected to the terminal→Yes
  2. reset the display menu -> Yes, but the problem is not solved
  3. connect to other terminals→Connect to HDMI terminal→No problem
  4. exchange to other DP cable -> not done because there is no other DP cable
  5. connect to other terminal -> try to connect to other notebook PC, but it does not show up as well (= it used to show up with the same cable and terminal)
  6. after turning off the display, unplug all cables and outlets, press the power button on the display itself a couple of times and leave it for up to 6 hours (discharge) → Solution!

Conclusion

First of all, you should try discharging the battery. You can suspect other things after that.