you should try doing diffrent upgrade combinations, some give more unspent points, that gives you bonuses from other upgrades, and buying the most expensive ones make you have more unspent points, i recommend firstly buying the most expensive, then when you don't have money on fourth research, you undo last upgrade and buy fourth reaserch, then buy the rest, i'm stuck on moment where you don't have enough points to buy one upgrade, all chargers are maxed, and i have like 0.11% compleate box, and upgrading upgrades doesn't do much
anyways, fun game