This issue is either caused by a faulty memory chip (NAND) or the Soldering under the NAND.
I honestly can't remember if the chip itself is failing, but either way, this is a job that can only be performed by an experienced microsolderer. This chip is soldered but also underfilled. This means there are dozens of metal balls connecting the pads of the memory chip to the pads on the motherboard. The space in between them is them filled with glue.
If you attempt to "reflow" (remelt the solder under) this chip you will fail as the expanding liquid volume will exploded out of gaps in the underfill, causing multiple short circuits.
You can remove the chip entirely by getting the chip up to soldering temperature by simultaneously scraping a knife blade through the underfill to release the chip. Accomplishing this without damaging the NAND or damaging the pads on the motherboard requires experience and skill.
Resoldering the same chip would require carefully removing all old solder and underfill from the bottom of the NAND, then using a purpose built stencil to aid in the placement of summer paste. But if the original chip is bad, replacing the NAND it's the only option.