The Atari 2600 power supply wasn’t as durable as the rest of the Atari 2600, which is nearly bulletproof. By far the most common issue with the Atari 2600 is a dead AC adapter. Fortunately, a suitable Atari 2600 AC adapter isn’t hard to find, even today.
After you replace it with something new, or at least newer, a dead Atari console usually springs right back to life. And if you’re wondering, the same problems apply to Atari 2600 clones like the private-label Sears Video Arcade and the Coleco Gemini and they can also use the same replacement power supplies.