Boot Device Not Found - Please Install an operating system on your hard disk - hard disk (3FO) F2

[tcos]

HP envy 360 (made 5/17 ) was working just fine. I loaded some digital movies and all was still fine. Now after start up, I have Boot Device Not Found and, after running System Diagnostics - hard drive quick check - I still show Boot Device Not Found.   T I used F10 and F9 then I went into BIOS and I switched from UEFI to Legacy start up modes and still showing Boot Device Not Found.  I did disabled the BIOS from USB start up because I had a 1TB storage device attached at one point.  Thinking back I am not sure if the screen show differently  (from Boot Device Not Found only) but now the complete black screen message is 

Boot Device Not Found -

Please Install an operating system on your hard disk

hard disk (3FO)

F2 System Diagnostics 

I tried the power reset options (Envy does not have a removable battery door) using the 15 second hold of the power button on start up.   same screen resulted (as above) 

Should I try the internal hard drive reseat by battery removal and hard drive reseat?   Should I take it for professional service?

I have data recovery concerns as I have small business LLC files stored. 

What's next?  I did not yet try to remove the battery and reseat the  

[WAWood]

@tcos 

New laptops that come with Win10 preloaded have that installed in UEFI mode -- so changing to Legacy mode will ensure that Windows no longer boots.  You need to go into Settings and change it back to UEFI mode before you do anything else.

This issue is often due to a failing drive. So, let's check that first, because if it is failing, it would need to be replaced and there is no point then in doing anything else until we confirm that.

Since your PC is new enough to support UEFI, you can use these steps to test the hard drive: http://support.hp.com/us-en/document/c00439024