As others have said, they are MJE13003s, a common bipolar power
transistor.
But since the lamp lit for a few seconds, any replacements are likely to
blow as well. There is something else wrong with the ballast.

Why didn't you just take it back where you bought it?

--- sam

Years ago someone at a car boot sale came by a large quantity of Ikea CFLs
which were presumably factory seconds as they "dropped like flies", I waited
until the seller dropped the price from £2 to 50p - at the time the cheapest
in the shops was over £10. A significant proportion of the boot sale CFLs
blew due to faulty tubes, as I was in the habit of repairing them I
reconstructed a few with small straight tubes secured to the holes where the
original tubes entered the casing. with a ty-wrap and wired in.

By the time all the Ikea CFLs I bought had become BER the shop price had
fallen to about £6.50p, at this price they were still worth repairing but
more recently the Morrisons supermarket (UK) has been selling it's own brand
CFLs for £1.99p and a couple of months ago launched a promotion selling
Philips CFLs (regular price about £3.50p) at 99p in addition to that they
ran a buy one get one free for a while - so the CFLs were going out the door
for only 50p each! - I bought a couple of carrier bags full at that price,
at that price there's no way I'm going to bother repairing any that fail and
the cost of petrol to go and return it would be more than the value of the
goods!