1999 v6 Toyota Avalon with 3.0l engine with 1mz engine crank no start

A client called me to fix his 1999 Toyota Avalon car with a v6 engine that cranked but wasn't starting.
After engine rebuild and gear oil replaced . While test driving by the engineer , smoke started emanating from the engine bay. Precisely, from the fan relay that the car owner connected by himself. Within few minutes, the car shutdown by itself as if fuel is finished.

Presently, it's a crank a crank no start, no spark, no injector pulse, check engine light staying ON with ECU connected or removed.
I tried to scan for DTC codes, but my scanner wasn't communicating. I checked all fuses, power and ground at obd port, those checked ok. but my scanner isn't compatible to read CAN network. There are only 4 wires intact for the obd2 port.
Furthermore, I added fuel through the intake to the engine, no change at all. I checked for spark and injector pulse. These things weren't present. But there was power to injector with just the key at ignition or ACC and COP had 1 ground and 1 power as usual.
With the ECU removed battery connected, Engine light would come ON. with ECU connected check light still comes ON.
Before I left, I checked the MAF sensor 5 wires and noticed that 3 wires were earth instead of 2 and 1 power; no ignition current/ power was available for the remaining 2 wires.
Please, what should I do
to get this car running again?

crank no start

The ECM's not involved for cranking.

there was power to injector with just the key at ignition or ACC and COP had 1 ground and 1 power as usual.

Power to injectors and coils comes from IGN fuse, and IGN fuse gets power from ignition switch in start or run, not in the accessory position. The ignitor should have a power and a ground and the 2 wire COP gets a ground from the ignitor to get ready to spark.

With the ECU removed battery connected, Engine light would come ON

Does the light come on with the key out, ecm out and battery connected? Check for short to ground on this MIL control wire.

I checked the MAF sensor 5 wires and noticed that 3 wires were earth instead of 2 and 1 power; no ignition current/ power was available for the remaining 2 wires.

B+ at MAF comes from EFI relay and the computer switches that on along with the circuit opening relay so the fuel pump can get power. Can you hear it coming on at key on? Do you have 5V at the MAF with the MAF unplugged? If not check powers and grounds at the ECM.

Sorry, the guide you rendered wasn't seen on time. Today, I went to check some things in the car . However, there was no good battery that was capable to crank the engine it could only be used to perform some test with testlight . The client apologized for that.
Nevertheless, I did some basic test. I checked the fuses the were all ok. I found the fuse that powered the MAF sensor wire that was supposed to be power instead of ground. When I unplugged the fuses, number 19 of it shutdown the light in testlight but put on the light whenever that fuse is reconnected. That's how the fuse for that location looked. Fuse number 6 shutdown the ECU light on the dashboard/ instrument cluster but comes back on when fuse was reconnected.
Additionally, I noticed that that particular MAF sensor wire illuminated the testlight even with the ECU removed. Using multimeter I checked and saw that that particular MAF sensor wire goes to one of the ECU connector.
Also checked the 3 front out of 6 fuel injector wire to ECU, they were not shorted. Still good! How can I follow up and solve the issues to get the car running again?

I'm looking all over service info for that fusebox you posted but could not find it except in model year 2000. 1999 MY (model year) has three 2 wire coils, 1 ignitor, and is a waste spark system whereas the 2000 MY has a 4 wire COP coil per cylinder. Is this correct? The correct wiring diagram is critical here.

Also service info does not assign fuse numbers to fuses so I'm unable to follow your train of discoveries completely. Can you post a picture of the fuse numbers and what they power, specifically fuse 19 and fuse 6?

Good evening sir. I went there yesterday to conduct some test in the car and noticed that, no iota of fuel was forth coming from the fuel pump on ignition On and during cranking. Scanner still didn't communicate. No spark no injector pulse still remained.

The first is the no fuel after I loosed the 14mm bolt slightly. Second is the power distribution layout for inside the video, while the last one is the engine room power distribution layout.
In addition, I swapped the EFI no change at all. When I tested for powers and ground, in one of the relay in the fuse compartment, the a/f relay was actuated. Please what checks should I further embark on, to rectify the issue?

you said there was smoke from a relay i would stat there and look for opean s or shorts in wirng in fuse box