Depreciation

1. ITR -4 is only for those assessees who are showing profit u/s 44AD, 44ADA and sec 44AE (Presumptive taxation scheme) 
2. If you wanted to claim depreciation ITR-3 can be utilized and full PL and BS should be filled up. 
3. Since you have income from PGBP, there should be a PL and BS along with that. In that Depreciation on FA can be claimed as per IT act and file the same. It is important to note here is, that once PL and BS is filled for one year, it would be wise to do the same for subsequent years (unless showing profit under presumptive taxation) 
Please correct me if the above solution has an alternative view.