"Upgrading" 1st gen Evolve Bamboo (newbie)

Hey guys, love your work in the forum. This place is very active and i was amazed by some of the designs i saw here from you guys. So about me, i bought an evolve first gen bamboo series on gumtree a couple of weeks ago, I was rally happy, until the board started to have issues. Fully charged going uphill (5 to 10 degree slope maybe) the motor stopped working and there was no power anymore and i had to pushkick, after 1 minute it was fine again and the motor was working, but everytime i hit full speed the same problem occured (no power from the motor).I have to say i am a big guy at about 105kg, dont know how much this plays a role.

Because i was a electric skateboard virgin i didnt know what to do and contacted the support, they told me to send in the battery and they would check the battery. So they contacted me and told me, that it looks like that the battery is not in prime condition anymore. So i thought i might do it myself and learn something new about batteries, motors and all that stuff, it turned out to be really interesting and the last two or three days i have read a lot about building batteries and what to look out for, but i still have a lot of questions to you guys who have way more experience and I was hoping maybe i can learn something off you.

So my plan is to build a new battery with 18650 cells and soder it together, i saw people using nickel strips and some using copper wires, what is the reason, or advantages/disadvantages? And what bms should i use, what diferences can be there? The original battery is a LiPo with 37v and 7Ah, i guess i can just attatch it to the esc and would be good?

And a question about vescs, basically it doesnt matter wich company i go with enertion/ollin/torque, just a question of supply? And when is it good to get a vesc with heatsink? (using a high current build?)

And last question for now about motors, what should i look out for (if i upgrade it) what are good brands (alien/enertion…)?

So thanks already and sorry for any grammar/spelling mistakes