Need help diagnosing fault with Panasonic KX-TGA520 handset

[bte]

Hi all,

I need help figuring out why one of the handsets of our Panasonic KX-TG5240 phone developed a strange fault. I attached a small clip to show the problems (I had to put it in a zip archive since forum software doesn't allow attachments with mp4 extension):

1- One of the screens is dim and there's a lot of flicker.
2- Cursor-like blinking (like when entering a name or number) happens randomly in various screens.

I first tried a new battery but that didn't help. Then I decided to open the handset and check the circuit. While there, I tried powering the handset from a RD-6006P power supply, set at 3.8V and 400mA. This also didn't help, either (the handset never consumed more than 150 mA and this is how I made the clip attached to this post).

Then I thought "maybe the caps are causing the issue". I measured the two main caps using DER-EE DE-5000 at 100 Hz. 330uF read about 288 and 100uF read about 84 so I changed them both (the phone is about 20 years old). The blinking issue improved a bit but it didn't go away (the clip is made after the replacement). Nothing changed with respect to the dimming/flicker issue. I also attached a picture of the circuit board.

I would appreciate any insight as to the direction I need to take from here.