Inspiron 13 7378 2-in-1 extremely slow after 1 year of working perfectly. Any suggestions?

I have a relatives Inspiron 13 7378 2-in-1 extremely slow after 1 year of working perfectly.

In the past few months this computer for any operations just takes minutes. The task manager claims nothing is being used, but even typing into the search bar and I am waiting for the typed letters to appears. If I do something in a browser like login to Outlook online (office365) and function takes a few minutes. I have even tried to replace the HD with a WD m.2 SATA Blue, but other then the added capacity nothing has changed... I tried diagnostics, says all hardware is fine, tried the Support Assist system default after loading OS from the cloud, I tried loading my own clean copy of Windows 10 and upgrading all drivers and OS to 1903. I tried different memory modules.... What else can it be? It acts like a crippled CPU, but could the last few BIOS updates crippled the machines performance for every one or just this one? I am not sure what else to try other then down grading the BIOS and disconnecting the battery (based on earlier post). Does any both have any other suggestions in the community?

Thanks,

S