I'd suggest to double check the main battery connections as it sounds to me like they may not be fitting very well on your new battery or may just not be tight enough or they coudl be corroded
So I'd suggest to use a wire brush on both connectors and the battery post and then refit and tighten so they are snug fit
also check the condition of the main engine earth connection and if any of the high power (40A +) fuses are corroded or broken
do you still need help?
Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you