Hi. No probs. I'm a sucker for punishment.
This is the normal boot sequence (taken from the manual, with added emphasis):
1. Red Power LED and green ACT (Activity) LED turn on
2. Red LED stays on, green LED turns off
3. A rainbow splash screen appears on the monitor (if connected)
4. Rainbow screen turns off, text scrolls on the monitor, green SD card activity LED flashes rapidly
5. Linux login prompt appears on the monitor
6. Green LED continues to flash a few seconds while software is loading from the SD card
7. Rune UI can now be invoked in a browser
So what you're saying is happening can't be happening. Unless you've changed a
lot more than you say you have.
Just to be clear: you are using a HDMI cable connected to a standalone PC monitor? Nothing else is connected to the monitor? No other equipment is running other than the Pi, the keyboard and the monitor? You don't need a mouse. Get rid of it. You don't need another computer. Turn it off.
If what you are describing still happens under these conditions then you're either the unluckiest person on this forum, or you've changed more than you say you have.
And you have two options: reflash the SD card or set up a Linux OS and access the Rune files with an SD card reader.