x5 engine eill not turnover

[rupe]

any help on my 2001 x5, it's sit for about a year and the bettery drain dead, i replace the battery and it will not start, the engine will not turnover, will here some relay clicking and all light will flicker. i recharge the battery but no help same thing.
i don;t if the key lost it;s memory if so any help to reprograme or what i have to do
thank you