So you booked a ticket from YPR-SC but opted to board at DMM....? I can give you one more example here of my recent stint. Now what you can do is goto nearest PRS resrvation counter and apply for change of baording point to YPR. Since you already have a reseravation from YPR to SC on the same PNR, they would change your boarding to YPR... no fee charged...The example i wanted to give is, I wanted to travel from JHS to DMM by KTK Sampark Kranthi, it was PLQL4 in 3AC. But I had 15 available from NZM to DMM. So I booked a ticket from NZM to DMM opting to board at JHS. This still put me in JHS quota. But I had the option to change the Boarding point to NZM personally through a PRS counter. Now what I did, instead of taking a chance, I cancelled this...
more... ticket and booked a ticket from NZM to DMM keeping NZM as the boarding point. Then visited the PRS counter and changed the Borading to JHS. Both the case are equivallant and get you a seat. The only difference is in which BP' quota would you fall. In your case only the first option of changing the Boarding point to YPR shall work. Please goto PRS and try to do that ASAP. If you are not doing that, since you already have a ticket, from YPR to SC, you will only be collected a fine of 250-500/- rs for travel without berth allotment. techincally even though you have paid to travel from YPR, you are still not eligible to travel as you don;t have a berth alloted. If the TC can take it easy, you will be good.