Have you ever updated the graphics driver(s) from Lenovo's Web site at all? If you didn't, then there is a new update dated October 4, 2020 for that laptop. The P50 does not support DCH drivers at all - only legacy drivers, as configured. That's why the Intel DCH driver installation failed. And please note that this software updates both the Intel and the Nvidia (in your case, the Quadro M1000M) GPUs.
And the Quadro M1000M and other first-gen Maxwell GPUs that have Compute Capability 5.0 have now had their CUDA support depreciated in newer Nvidia drivers: Version 440 introduced CUDA 10.2, which began locking down CUDA support for the GM1xx GPUs (including your Quadro M1000M) to CUDA 10.1 compatibility levels, and this support continued into CUDA 11.0, 11.1 and 11.2 (introduced with the 450-, 455- and 460-series drivers, respectively). Thus, as time goes forward, your laptop's Quadro M1000M will no longer be usable for CUDA GPU acceleration in a future Nvidia driver release.
And do not rely on Microsoft Update for the graphics drivers! Microsoft Update checks only the Microsoft Web site for the driver, and the most recent driver that is compatible with your hardware that's available from the Microsoft site just now happened to be more than a year old.