BIOS recovery typically wants the .rcv file on a 1- or 2- GB USB, and certainly not on a 128 GB USB or a SATA drive. Have you replaced the motherboard battery? You probably should do that, even if only to rule the battery out, before going any further: If it still won't boot, try running the PSU BIST, using the instructions at that link for PCs with a PSU test button on the back. BTW: Since this PC has an add-in video card, make sure the monitor is connected to that card, not to the onboard AMD HDMI port.
I've been recently come into posession of a Dell 5675 desktop pc, (Ryzen 1400, 2133MHZ ddr4 ram, GT745) And it looks like ive been hit with a corrupted BIOS issue. (Power button blinks 6 white, 3 orange and repeats) At first the PC had a ryzen 1600x and it showed no signs of life beyond spining the CPU fan. Once I placed in the Ryzen 1400 (non-x), did the systems blue LED light bars flash up and the fan spinning. However that is the limit to the amount of  activity the PC shows. I have followed the steps here: [URL] holding down CTRL+ESC, having that BIOS_IMG.rcv file on a FAT32 formatted usb drive ( a junky 1gb drive and a 128gb usb 3.0 drive) in the USB 2.0 ports and then powering up the PC does nothing. I dont see any video output The USB keyboard doesnt show any signs that its recieving power. I've tried the same on a PS2 keyboard but beyond the single flick of all three keyboard lights on first boot (caps, num. scroll lights) no response. I've tried 4 different GPU's both with the 6 pin, and no 6 pin PCI-e psu plugs and its still the same. I can see that the USB ports are pushing out power but im not sure if the data lines are active. I've tried the above method, BIOS_IMG.rcv file on a sata SSD but no luck. Replacement motherboards are too expensive and im trying to cut down on ewaste, so I'd really love to get this running. Is there something im doing wrong here? 
Dell Inspiron 5675 no post issue - BIOS problem