Primary Issue Requires Assistance

[DivineStripe]

I own a 2004 E46 2.5 and am experiencing an issue. The original key was in poor condition, appearing glued and dishevelled, prompting me to replace the entire key fob. I successfully transferred the chip and key to the new fob; however, upon attempting to start the vehicle, the ignition activates but the engine does not crank. I recall unlocking the car with the new key, yet it fails to start. I suspected a battery issue and attempted a jump start, but the engine remains unresponsive. I would appreciate any assistance or insights regarding this problem. Thank you in advance.

[AbdulBMWi3]

The transponder within the key is quite fragile and may be compromised, or, if fortunate, it may just be failing to establish proper contact with the key blade, which transmits the immobiliser code to the ignition.

[DivineStripe]

Can I rectify it?

[AbdulBMWi3]

If it is merely failing to establish a proper connection with the key blade, then sure; however, if the transponder is compromised, no, unless you can procure a replacement transponder, solder it in, and have the technician program it into the vehicle's ECU, which I doubt you can do.
If I were in the UK and the contact to the blade was not compromised, I would seek a new key from an auto locksmith, as their services are more economical than those of a BMW dealer in the UK.

[craigstomer]

I cannot claim to have performed that task, but I recall my sister purchasing a remote key from eBay.
She enquired whether I could make it functional; nevertheless, it contained a black chip component, and I refrained from further since I lacked the coding capability.
Did your key contain any small adhesive residue that you failed to transfer?

It was merely a consideration.

[DivineStripe]

I am uncertain if you are aware, but I attempted the old key as well, nevertheless it remains ineffective.

[DivineStripe]