Bijoy is right,If Backplane is replaced and is OK then further need to check.
1-TSC & BCC should be same,
2-check for FRU,FRL valus
3-Check for MAIO OFF set
4-Convert TRX Traffic Channel mode to TCHD instead of TCHH or TCHF.
Hope will be Helpful
I have Experienced problem and was resolved by checnging TCHF to TCHD.that can be cheked by ZERO Command…