RC car dead, no throttle, ESC light blinking or beeping? Check battery, switch, bind and ESC codes in order, then tell a bad ESC from a bad motor. Most take minutes.
Start with the cheap causes. Most dead RC cars have a flat or storage-charged battery, dead transmitter batteries, a failed switch, or a receiver that lost its bind. Turn the transmitter on first, then the car, and watch what the ESC light does. That light tells you which half of the car to look at.
Most likely. A pack that sat on the shelf may be at storage voltage (about 3.8V per cell), which runs but only for half a run. One that sat for months may have drifted low enough to trip the ESC's low-voltage cutoff as soon as you pull the trigger. Charge it and try again before anything else.
A $15 multimeter settles it. Measure across the main plug: a full 2S LiPo reads about 8.4V, a full 3S about 12.6V, and a 7.2V NiMH about 8.4V fresh off the charger. Anything well under nominal (7.4V for 2S, 11.1V for 3S) is your problem. A LiPo with one cell much lower than the others at the balance plug is on its way out.
Also check the plug itself. A bullet that's been pulled a hundred times gets loose and loses contact under load.
The on/off switch is the flimsiest part of most cars. Wiggle it with the car on. If the ESC light flickers, that's your fault. You can bypass it temporarily by unplugging the switch harness and bridging it, or replace it for a few dollars.
Weak AAs in the transmitter cause range loss, failed binds and glitching before the low-battery beep ever sounds. Put fresh cells in; it takes thirty seconds and rules it out.
Check throttle trim too. If the trim was knocked, the ESC sees "throttle on" at startup and refuses to arm, usually with a warning blink.
If the ESC lights up but nothing responds, the receiver may have lost its pairing. The steps vary by brand, but usually: transmitter off, press and hold the receiver's bind button (or fit the bind plug), power the car, then power the transmitter while holding its bind button. The receiver LED goes solid when it's done. Your manual has the exact order. More on how the pair works in transmitter and receiver basics.
While you're there, check the receiver's channels: the steering servo goes in channel 1 and the ESC in channel 2 on almost every surface radio. A lead that got knocked out or moved in a crash is a common "dead car".
Patterns differ between Hobbywing, Castle, Spektrum and Traxxas, so check the manual for your model rather than a forum post about a different one. The general meanings:
If the car started acting up after a crash or a battery swap, recalibrate the ESC to the transmitter (neutral, full throttle, full brake). It's a two-minute job in the manual and it fixes a lot of "throttle does nothing" cases.
Unplug the motor and power up. If the ESC now arms normally, the ESC is probably fine and the motor is suspect. If it still errors with nothing connected, the ESC is the problem.
A brushed motor with worn brushes runs weak, stutters or only works in one direction. A brushless motor usually fails loudly: a burnt smell, a phase wire that got too hot, or the ESC reporting over-temperature every time you try. If the motor runs but gets too hot to hold after a few minutes, you're overgeared or something's dragging, which is covered in pinion and spur gearing.
Once you know which part died, you're buying one part rather than guessing. Used ESCs and motors from someone's parted-out car turn up in the listings, and the deals page tracks new ones on sale. Checking joints and connectors after hard crashes is part of post-run maintenance.