Disconnect the battery for a couple of minutes to see if codes clear. If not, check the opti wire harness. Check it out fully, that means connector themselves, pins for corrosion, bent, burnt. Check the wire visually and with an ohm meter to see if there's too much resistance.
If all is well with opti wiring, but code 16 and?or 36 come back, go to sticky threads of this section and open the diagnosing the opti thread. Watch the video and run the tests.
When you changed the icm, did you put heat sink compound on it's back and on the heat sink? If not you can burn up the icm in short order.