The why is more to do with this example. The wings missing, the nerf bar that is still with it is broken, other one missing, half the chrome effect has worn off the plastic, it's scratched, the decals are damaged, and it only goes backwards, so why for the love of cheese am I wasting time on it? There's no emotional attachment to me either.
Thing is I love my daughter and her partner picked this up and then saw an eBay add that showed a mint in box titled "rare collectible" going for £150 ........ Most of them go for £50, so he's convinced he's done well and I restore these things right!
It's not mint , there's no box and even then it's only worth £50-£60 .....hah!
Well first of I thought I'd look at the control board (Rx/ESC combo) to see if I could get it going forward as well as reverse, there's only 4 fets on two big heat sinks so I'm thinking two for forward and two for reverse, none look burned, now I've had this reflow station for a while and only used the soldering iron not the reflow tool so this is ripe for a test. So I go over the board reflowing, for anybody who's not sure the reflow tool is like a miniature hot air gun that is thermostat controlled and the blowing force is controllable on some as well, the idea is to just remelt the solder to fix micro cracks without overheating components, well after the reflow it goes forward YAY! Now it won't go backwards.

The next thing was the nerf bars, a bit of 3d sketching in Fusion 360 and we have this(3d sketching is, well it's hard to explain but it does odd things that are like putting my brain in a micro wave oven ), it's black because I just couldn't colour Mach the grey.
It's not exact but it had to be possible to 3d print it, it's FDM (filament) printed then painted with 3d printer resin to smooth out layer lines, then painted with ...well paint.

Think they look good enough.