Night Hawk R7000 upgrade failure

Here's the full story to help anyone provide some insight into what my next steps might be.

1. I had a R7000/AC1900 running for about a year running 1.0.9.34. It was working fine. I have it connected to a ARRIS cable modem with a 1 gig uplink, and connected downstream to two 16-port switches, using gig connections. The router was left in its default settings from the factory, with router address of 192.168.1.1

2. I received an email from Netgear awhile back suggesting that there was a security concern and I should upgrade to 1.0.9.42. 

3. So I went to the NETGEAR website and downloaded the CHK file to my PC.

4. My PC is a Windows machine, runnning Version 10, April 2018 build (official). The PC is attached via hardwire to the Gigabit switch and was assigned a static address of 192.168.1.30 and is using a subnet mask of 255.255.255.0  I am using the COMCAST specified DNS entry of 75.75.75.75

5. For the past year, this PC has been successfully accessing the internet, with download speeds of 300Meg and Upload of 12Meg

6. From the PC, I logged into the router via the CHROME browser to access the R7000's Firmware update screen and pointed to the 1.0.9.42 CHK file and told it to Upgrade. It never came back and my internet was no longer reachable.

7. I left it for 2 hours and then I repowered the router itself. The single LED on the left, the POWER LED, is now blinking WHITE which seems to say the firmware is corrupted (according to the Netgear KB here: https://kb.netgear.com/23991/What-are-the-LEDs-and-ports-on-the-front-panel-of-my-Nighthawk-router-called)

7. I plugged a laptop into the cable modem itself and able to establish and confirm successful connection to the internet, which it was, but the R7000 router was now definately offline.

8. I went back to my PC (with a static 192.168.1.30 address) which is still hardwired to the switch which is hardwired to the R7000 router and tried to access the router, which was now NOT reachable. I tried the EDGE browser and CHROME browsers by entering "192.168.1.1" into the address bar. Both failed as unreachable. The Router POWER LED is still blinking WHITE

9. On the PC, I opened a CMD box, and got the familiar "DOS-Box" window with the "C:User>" prompt.

10. I typed "Ping 192.168.1.1" and recieved the notices "Request Timed Out." over and over.

11. I also tried typing "tftp -i 192.168.1.1 put 1.0.9.42.chk" and get the "Connect request failed" message

12. I typed "Ping 192.168.1.30" (the PC's own address), to confirm the network stack on the PC was operational and got the four success messages. And I even typed "Ping 192.168.1.22" which was the IP address of my HP Printer hardwired to the same switch and received four correct/successful Bytes=32 Time=4ms TTL=64 messages.

13. I tried to factory RESET the box. I put a paper clip into the RESET hole and heard the click, held it for 30 seconds, then while holding it removed power and left it unplugged for 30 seconds, and then reapplied power and kept holding the paper clip for another 30 seconds. (Paperclip was pressed for a total of 90 seconds). The box repowered, POWER LED stayed amber for perhaps 30-40 seconds, and then started BLINKING WHITE again.

13. Finally I tried opening a CMD box again on my PC and at the "C:User>" prompt, tried "PING 192.168.1.1" from my PC which is still hardwired to the switch which is hardwired to the router and my PC still has a static address of 192.168.1.30. Router is still not reachable and I get "Request Timeout" messages.

Does anyone have any suggestion on what I may be able to do now with what appears to be corrupted firmware and no communication to the outside world? I would prefer not to open the box. (I saw one thread about opening the box and using a serial USB cable to access the LINUX console to manually start the TFTPD, but this is unfamiliar territory for me which I would rather avoid if possible).