Its likely to be broken as flashing lights indicate some sort of diag code. If you have 1 year warranty from the battery supplier sort it out with them which will normally require u to return the battery to them.

I bought the battery through dell

then contact dell as the battery should come with a one year warranty.

1-3-5 means u have a dead battery. also ur battery's warranty is diff from ur system's warranty. it will only have until 1 year so if it's within 1 year try calling dell techs support and also take note of the 1-3-5 code so that you wont have to explain anything. we will be also needing your battery's PPID its on a sticker attached to ur battery. we will be needing that before we complete the dispatch.