RockPi 4B, possible defect RAM?

#1

Hi

I have two RockPi 4B 1GB that, most of the time, don’t boot and the blue LED doesn’t light up either.
Using a serial cable pointed out the RAM could be the problem and if I apply a little pressure on the RAM modules while turning on the RockPi, it actually boots up!

Is that a known issue?

DDR Version 1.20 20190314
In
channel 0
CS = 0
DDR Version 1.20 20190314
In
channel 0
CS = 0
MR0=0x19
MR4=0x3
MR5=0x6
MR8=0x0
MR12=0x72
MR14=0x72
MR18=0x0
MR19=0x0
MR24=0x8
MR25=0xFF
channel 1
CS = 0
MR0=0x19
MR4=0x3
MR5=0x6
MR8=0x0
MR12=0x72
MR14=0x72
MR18=0x0
MR19=0x0
MR24=0x8
MR25=0xFF
channel 0 training failed!
channel 1 training failed!
change freq to 400MHz 0,1
channel 0
CS = 0
MR0=0x19
MR4=0x3
MR5=0x6
MR8=0x0
MR12=0x72
MR14=0x72
MR18=0x0
MR19=0x0
MR24=0x8
MR25=0xFF
channel 1
CS = 0

#2

It is possible that RAM module is ok but not its connection to the board. One of the options.

#3

It seems the dram chip soldering issue. If you have hot air gun, you can try to use it to blow the dram chip area. How long have you been using these ROCK Pi 4?