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A2116 / 2019 / 3.6 GHz quad-core i3, 3.0 GHz 6-core i5, or 3.2 GHz 6-core i7 processor. Released March 19, 2019.

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No boot, led 1 and 2 on, fan spinning

Greetings.

Someone brought me an iMac 21.5” - 2019 - which doesn’t chime and doesn’t boot. The fan spins normally when a screen is attached and - as expected - very loud without a display. There’s no hd nor sata cable. There’s a working ssd on the backside of the logic board: it works because I successfully mounted it on a different machine for testing. The screen is smashed and the chassis shows signs of a heavy impact. Only led 1 and 2 are on. Both leds light up as soon as the power cord is inserted. An external display remains black too. SMC reset did nothing, PRAM reset is impossible since the usb-keyboard is not active.

When I removed the screen, all stickers were in place (on lower left screw of logic board, all 4 screws on heatsink), showing that the logic board had not been removed before I did.

Can anyone help, please?

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I suspected cpu or graphics card. Replaced cpu with a known good one. Problem solved. The machine now works perfectly.

Thanks.

完成的

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If this suffered a hard impact, I'd do a pretty thorough inspection for physical damage before moving on. Look for loose parts in the case or any large components (like capacitors on the power supply) which are damaged or dislodged. Check the RAM and sockets to make sure they're in good shape too.

If all looks good physically, I'd move on to testing the individual power supply voltage rails to make sure power is actually good everywhere it needs to be. There could be a short somewhere from the impact damage which could be causing problems.

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Massimo Oriano 将永远感激不已
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