Dell XPS 15 9550 Very Slow Boot + 32GB SSD not detected

Dear Community,

I have an unexpected Blue Screen event and was ill-advised to immediately reinstall Windows 10 OS. I did successfully reinstall, but on Legacy BIOS. I decided to reinstall once more in UEFI - which i did using Diskpart - Convert GPT command. It was successful install - RAID, RST drivers, BIOS update and all drivers from Dell. I have two issues:

1. The 32 GB SSD is no longer detected by the RST console.

2. The laptop takes 3 minutes to boot - 2 minutes for Pre-Boot (Dell logo is plastered on Screen) and 1 minute for Windows to load.

Performance wise, I only noticed heat buildup on the general keyboard and left and right sides (where you rest your palms wen typing). I only use Word and Edge (no other application running).

Can anyone please direct me how to fix the two issues above?

Thank you.

Dominic

Dell XPS 15 9550

i7-6700HQ

NVIDIA GeForce GT 960M (2 GB)

16 GB RAM

32 GB SSD

1 TB HDD