My phone doesn´t turn on after update

So I did a downgrade to my moto g6 from android 9 to 8.
It worked fine, but it got an official security patch update, wich I put to install, but when the update installation finished my phone just died, now it doesn´t turn on, even the boot menu doesn´t show up, if I connect it to charge a blinking light appears.
I dont know what to do but ask for help.

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