All-
I’m somewhat new to Mikrotik and have been clicking where I should not have 
I logged into my 450G via Winbox and attempted to downgrade from 5.6 to 4.17. I clicked on “uninstall” and rebooted. Now, I can’t see the router on my network nor can I access it. I’ve tried reset but nothing. Could someone please get me back on track. Thank you in advance for your help.
fewi-
Thank you! 
Do you know whether there is another alternative than the one you offered? I ask only because my SFF computer lacks the serial port that Netinstall requires, and I don’t easily have access to a computer that does.
According to the manual (http://routerboard.com/pricelist/download_file.php?file_id=143) there is a reset jumper near the MicroSD slot, but on the top side. Short circuit that reset hole while booting to reset to factory defaults.
Since you have a unit with a serial port it would pay to buy a USB to serial adapter, though. You would likely be able to recover the router from the serial console without having to lose all other configuration.
Thank you for the additional information. I did short-circuit the reset hole but that action didn’t resolve my problem. Still unable to access. I’ll purchase the cable as you suggest and go from there.
Thank you!
Did you follow the reset instructions? You also need to cycle the power and wait for the LEDs to flash to reset to default config or until it stops flashing to have it look for a netinstall server. It may take a couple tries to get the timing right. See:
tjc-
Thank you for the information. Yes, I did try the reset procedure a couple times. Still no access.
Thanks
Okay, I’ve successfully logged into the 450G using hyperterminal. The router reboots, accepts the IP address, resolves the mac address but then stops at “jumping to kernel code.” In addition, the device does not show up in the netinstall window.
Help! I’m completely stuck and get past this “kernel code” notation. EDIT: when accessing other options, I receive a “kernel panic - not syncing: No init found. Try passing init= option to kernel”
Any suggestions are welcome.
Thank you!
The install is broken, and it can’t boot. You’ll have to NetInstall it, as that either failed before, or was done with a damaged image (try to download the image again before using NetInstall). The steps for NetInstall I initially posted here include the instructions on how to access the router via serial cable during boot and reconfigure the bootloader for NetInstall. Also keep an eye on the router via the serial cable/HyperTerminal during the entire NetInstall process and look for any error messages.
fewi-
Thanks. The new image fixed the problem. All is now good! I’ll be increasing your Karma count. Thanks again!