Encoder resistance ?
If I’m not mistaken, the encoder shouldn’t have any resistance, it should send “pulses” of HIGH/LOW ?
Have you tried reheating ALL the pins that somehow connect to the encoder? IE: All the pins on the encoder, then follow those to the atmega/shift register, reheat those pins, and so on, until you arrive at the atmega ?
Try checking for shorts between adjacent pins. Try checking that the corresponding MCU pins are not bent when the MCU has been inserted in the socket. The middle pin of the encoder is for ground, check that it is correctly soldered.
It’s quite difficult to monitor the signal coming out of the encoder pins without a logic analyzer
if you want to remive the lcd its best to cut the stacking connector between the baord ( its a 5ct part) ant then further cut it into individual pins and desilder these one by one
you can check connectivity from the pins of the MCU to wherever you want without taking out the LCD.
however, if there’s something bad underneath it then fcd72’s advice is the best. just make sure you do not bend the header pins while cutting to avoid pads coming off.
i have successfully desoldered some LCDs from Shruthi’s but it’s a troublesome desolder wick party and requires some patience, not really worth the easy to get header.
good luck