Why is it malfunctioning after replacing the battery?

I have replaced the battery as directed. The display lit up, with a blank screen upon powering up...but that's all. After approximately 2 minutes it beeped twice, and there were dark bands on the lower area of the LCD display. Now it just beeps every 2 minutes.

After being plugged into a charging dock for 30+ minutes the lower half of the display has alternating bands of black and dark grey, and is still beeping twice every 2 minutes.

I used a soldering iron that was not calibrated...might I have fried the pcb?