According to these pictures, you have inserted the flexible pcb (cable) upside down (pay attention to the contacts):
You should correct this, and try it again. Please also note the following comment in the linked thread regarding the correct insertion of the M.2 NVMe SSD.
Additional be ensure that you chosen a M.2 NVMe SSD (Key-M) not M.2 SATA SSD (Key-B and Key B&M). The maximum power consumption of the NVMe must not exceed 5 W.