HP 4155 Embedded Web Server stopped working after setting SSL certificate

[fizbin1]

My printer was set up and working on my wifi network; the only issue was that the Embedded Web Server was using a self-signed SSL cert. (Red, broken-lock icon) I don't have a computer connected to it via USB, so it's all wifi.

To fix the red, broken-lock icon issue, I went through the Embedded Web Server menus to make an SSL certificate request and then created an SSL certificate for the printer. I uploaded it, the printer accepted it, but continued to use the self-signed SSL cert. (When I asked the printer to show the certificate, it showed the details of the certificate I uploaded) Therefore, I turned the printer off and on again.

Now, the printer will continue to work as a printer. I can send it print jobs from anywhere else on the network just fine.

However, the Embedded Web Server has halted. When I type "http://MYPRINTERIPADDRESS" into my web browser, nothing happens for a long time and eventually I get a message from my browser: ERR_EMPTY_RESPONSE. I have double-checked the IP address by having the printer print out the networking page. (by pressing the WiFi and Information buttons together) When I try "https://MYPRINTERADDRESS", and use tools to monitor the network, I see that the printer opens an SSL connection using the certificate I uploaded to it, but then never sends any data.

Again, it still works fine as a printer, but without access to the Embedded Web Server, I can't scan any documents which is kind of half the point of this device.

I suspect that the Embedded Web Server is unable to handle a custom SSL certificate. Is there any way to fully factory-reset the printer so that it forgets this custom SSL certificate and goes back to a self-signed one? Also, what are the limitations on SSL certs for the Embedded Web Server?

[fizbin1 · Accepted solution]

Looking around for different ways to hard-reset an HP printer, I eventually came across this method:

Pull the plug from the printer while it is on, then press and hold both the print and cancel buttons while another person pushes the plug back in. Keep the power and cancel buttons pushed for 20 seconds. A "Printer status report" page will print out.

This did not (as advertised) cause a factory reset on my printer. However, it caused something much better! My printer's Embedded Web Server started working again, and the best part is that it's now using the SSL certificate I generated for it, so no more red, broken icon! I don't know what exactly it reset, but something about that procedure made the Embedded Web Server work again.