If you've executed all the necessary flash set commands and are still experiencing connection issues, along with a misconfigured VLAN mapping, consider the following community-discovered fixes:
Multiple user report that Nokia/Alcatel OLT giving fake O5 with 02020202 OLT Vendor Id, this making hard to troubleshoot for end-user and vendor...
More information to negate this problem, read here
Some OLT (Fiberhome OLT) cause GPON Stick can't get O5, instead of looping between O2 to O5. See issue #131 of the Fix
Many ISP map VLAN differently from PON Interface and ETH Interface (example: VLAN 100 > 10). See issue #229 of the fix