Change of employer petition aka transfer is only possible while the beneficiary is already in the US working for H1B employer.
In your case the H1B employer can file new cap-exempt petition however USCIS may not approve it as your H1B is not activated either by H1B stamping or working for the H1B employer.
That said there are cases where USCIS has approved cap-exempt H1B even if the beneficiary never worked for the H1B sponsoring employer.
But just another question, will the denial of the new cap-exempt petition in anyway affect the current employer’s approved petition like making it void?