Oops - I didn’t wait for your reply and tar updated. Now my RF remote is not working and I’m stuck! I ssh’d in and checked that I had the right dtb and it looks right. I even tried the stable 9.2.3 and ensured that I had the right dtb, but no luck either. Any suggestions? I actually burned an sd card and copied the supposedly correct dtb, but even that didn’t respond to the remote. 
So what doesn’t work on your remote?
Nothing - totally unresponsive to any keys. It’s just a generic RF remote with USB dongle. Was working fine until I placed the tar file and re-booted. Now I can’t even get a clean sd card build to respond to any key press. What did you mean with “it will stick forever with the wrong dtb”?
I meant you will have to cp the correct dtb.
Those rf remotes work as keyboards so they work all the time. Power button could be IR so you need to set it up. Check if usb is working for you at all.
I had a similar thought (USB) and I’ve gone back to basics. Removed eMMC card and clicked the switch to point at the SPI. Plugged in standard USB keyboard. Petitboot loaded but I could not move the cursor with the keyboard. No lights on KB either. Tried with a mouse also - LED on mouse not lighting. Have I got a dead USB controller on the N2??? The power led is lighting, the heartbeat led is flashing, the HDMI is working, but no apparent output from USB - aargh!
Try to flash nightly N2 img.gz fresh on emmc or SD. Then boot. Now try a usb keyboard or usb flash drive and see what happens. If it doesn’t work ssh into it and post “dmesg”
Fresh nightly burned on SD card and booted from. Unfortunately, a clean install doesn’t allow SSH until you permit it during the install wizard - which I can’t cos USB doesn’t seem to work. 
I’ll go back to the eMMC - at least I can SSH into that… wait 5 mins please
Are you trying usb keyboard or only your rf remote?
I’ve tried USB keyboard - nothing. I’ve just booted again from eMMC and plugged in a USB stick which has a LED. It’s not lighting. I’ll SSH in and get dmesg.
I think something is broken. But let’s see them dmesg.
You don’t say! 
150 euros and it lasted all of two hours…
Yeah it looks broken. Bad luck.
Can you point me at anything specific in the dmesg regarding USB issues?
I see errors about low battery voltage in the RTC. That itself is weird as it should be brand new!
I’m heading to bed at this point so I won’t be responding to any other replies. Disappointed at such an early fail…
It’s because the driver doesn’t recognizes your 4 Port USB hub. It could be possible that the usb otg port still works. This is my N2+:
[ 1.489005@3] usb 1-1: new high-speed USB device number 2 using xhci-hcd
[ 1.639358@3] usb 1-1: New USB device found, idVendor=05e3, idProduct=0610
[ 1.639362@3] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1.639364@3] usb 1-1: Product: USB2.1 Hub
[ 1.639366@3] usb 1-1: Manufacturer: GenesysLogic
[ 1.640733@3] hub 1-1:1.0: USB hub found
[ 1.758236@0] usb 2-1: new SuperSpeed USB device number 2 using xhci-hcd
[ 1.780284@0] usb 2-1: New USB device found, idVendor=05e3, idProduct=0620
[ 1.780290@0] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 1.780292@0] usb 2-1: Product: USB3.1 Hub
[ 1.780295@0] usb 2-1: Manufacturer: GenesysLogic
[ 1.784852@0] hub 2-1:1.0: USB hub foundIs it possible that my install of the Amlogic-ng nightly of 20200728 tar has borked the USB detection in some way? How I did it was to copy the tar file into the Update directory from my desktop PC and then reboot the N2 from the remote control. I watched it as it detected the update, then applied it and re-booted. When Kodi loaded there was a changelog displayed on-screen and at that point my remote stopped working. I’ve booted the N2 on subsequent occasions with no eMMC or SD card installed (using SPI switch) - Petitboot loads but the USB ports seem dead. Is it possible that the power supply to the USB3 hub has been latched “off” by software? I tried plugging my phone into each of the USB ports in turn, but no indication of anything from the phone. Even when I plug the phone into my powered off PC, there is a chime to indicate a connection, even though there is insufficient voltage to start charging, so it should chime when I try the N2 USB3 ports. I’ll see if I can locate an OTG cable and try that.
I noticed that the Petitboot build date is back in December 2019. Would it be worthwhile trying to update that by SD card? I can’t help thinking that there is a software cause behind this problem, because the USB ports stopped working immediately after a reboot using the nightly build. I didn’t touch the box at the time, so there couldn’t/shouldn’t be an ESD issue causing it.
edit - OTG port is working. I have a microSD card adapter and it’s reading the contents ok. Don’t have any means of connecting a dongle to it as I can’t find a male/female cable to hand.
You can try to update petitboot.
I can not imagine that something in software disabled your USB. Are you 100% sure you have a N2+ and not a N2?
We can ping @tobetter. He is from Hardkernel. Otherwise I would try to return it and get a new one.
Also I have seen you say you have usb power to stay on. What exactly do you mean. Can you try to revert that.