BIOS not saving boot configuration

My Dell Inspiron desktop upon bootup goes to the black screen with the message:
Hard disk drive failure No Bootable Device Strike F1 key to continue, F2 to run setup utility

When I hit F1, I get:
No Boot Device available
Sata 0: None
Sata 1: Installed

Hitting F2 shows Sata 0: Empty Sata 1: the DVD drive

In the BIOS boot section it shows:UEFI mode
1st boot device: Internal HDD
2nd Boot device: USB
3rd boot device: Internal ODD
4th boot device: USB Floppy device
5th boot device: Onboard NIC

I can exit BIOS after saving changes and the computer will then boot up.
I can go into Windows Recovery, click on Update UEFI firmware settings and when it re-enters the BIOS, it shows:
Sata 0: HDD
Sata 1: DVD

In the BIOs boot section it shows: UEFI mode
1st boot device: UEFI: Windows Boot Manager
All other boot devices are the same as above.

I then exit the BIOS, saving all changes to this configuration. However, after shutting down the computer, upon the next power-up, it's back to the black screen with the No bootable Device message. In other words, back to square one.

I've replaced the CMOS battery 3 times. Made sure the SATA cables are secure and re-seated. Run the Dell ePSA tests..everything passes. The BIOS firmware is the latest version.

Here's the system info:

OS Name Microsoft Windows 10 Home
Version 10.0.14393 Build 14393
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name DELLCOMPUTER
System Manufacturer Dell Inc.
System Model Inspiron 3647
System Type x64-based PC
System SKU 0611
Processor Intel(R) Core(TM) i3-4150 CPU @ 3.50GHz, 3500 Mhz, 2 Core(s), 4 Logical Processor(s)
BIOS Version/Date Dell Inc. A08, 6/29/2015
SMBIOS Version 2.7
Embedded Controller Version 255.255
BIOS Mode UEFI
BaseBoard Manufacturer Dell Inc.
BaseBoard Model Not Available
BaseBoard Name Base Board
Platform Role Desktop
Secure Boot State On
PCR7 Configuration Binding Not Possible
Windows Directory C:\WINDOWS
System Directory C:\WINDOWS\system32
Boot Device \Device\HarddiskVolume1
Locale United States
Hardware Abstraction Layer Version = "10.0.14393.206"
User Name DellComputer\ansch_000
Time Zone Central Daylight Time
Installed Physical Memory (RAM) 8.00 GB
Total Physical Memory 7.92 GB
Available Physical Memory 4.92 GB
Total Virtual Memory 9.17 GB
Available Virtual Memory 5.98 GB
Page File Space 1.25 GB
Page File C:\pagefile.sys
Hyper-V - VM Monitor Mode Extensions Yes
Hyper-V - Second Level Address Translation Extensions Yes
Hyper-V - Virtualization Enabled in Firmware Yes
Hyper-V - Data Execution Protection Yes

What else can I try?
Thanks ahead of time.