Similar thing happened to my Arcadia T5 ballast, I did buy replacement holders and tried fitting them but the unit never worked again, since it was out of warranty I did nothing about it, still got it somewhere.
If its that new then complain where you purchased it.
As a leading manufacturer in the aquatic industry, we take very seriously our responsibility to provide high quality products, which are suitable for their intended purpose. We would advise that due to recent changes in EU regulations, the end caps in such systems now have to be waterproof and as the caps on our T5 systems are not, we are no longer able to supply these products. We are therefore unable to offer you a replacement starter unit.
We do appreciate that this will be disappointing to you and therefore in order to resolve this matter, we can either arrange for replacement T8 bulbs and starter unit to be despatched to you, or arrange for a refund to be issued which will then enable you to purchase alternative lights.
A welcome one as well as I wanted a refund not replacement.