Precision 5530 black screen

Hello,

When powering on the laptop:
- The keyboard LED are on
- We can ear the fans working
- But, the screen stays black
- Note: no beep are eared

I've done the following:

- Real-Time Clock (RTC Reset)
(cf https://www.dell.com/support/manuals/fr-fr/precision-15-5530-laptop/precision5530_servicemanual/real-time-clock-rtc-reset?guid=guid-c0d479fa-5458-4e9c-8250-7d1a5762fc99&lang=en-us)
  > issue still here

- Drain residual flea power (perform hard reset)
(cf https://www.dell.com/support/manuals/fr-fr/precision-15-5530-laptop/precision5530_servicemanual/drain-residual-flea-power-perform-hard-reset?guid=guid-2da79962-34ff-421b-8b91-39cbbb623ca0&lang=en-us)
  > issue still here

- Built-in self-test (BIST)
(cf https://www.dell.com/support/manuals/fr-fr/precision-15-5530-laptop/precision5530_servicemanual/built-in-self-test-bist?guid=guid-63d84cdd-b1bb-4328-a95f-b0b3636fe589&lang=en-us)
  > does not indicate a failure

- Remove/Reinstall the CMOS battery
(cf https://www.dell.com/support/manuals/fr-fr/precision-15-5530-laptop/precision5530_servicemanual/removing-the-coin-cell-battery?guid=guid-e10c3a37-f4a7-4567-85ad-61b1c4bacbd7&lang=en-us)
  > issue still here

- Using an external screen
  > issue still here

Any ideas what can I do next?

Thanks!