Extracting ROM from Lenovo

I have 2 Lenovos A358t. One has a faulty ROM flashed into it (only one available in Russian) and the other one wasn't messed around with (never broke) so it's in Russian AND works fine. I would like to extract the ROM/firmware from the working a358t and flash it to the faulty a358t.

Could anyone help me? I've never done anything of the sort, so I would need concise directions. Thanks

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