Here's the quickest thing to try first. Plug your Xperia 1 VI into a wall outlet using a known-good USB-C cable and a 30W USB-PD charger if you have one. Let it charge, undisturbed, for at least an hour. A completely drained battery can sometimes take a while to show any sign of life, even on the charging indicator.
If you see no light or screen response after that long charge, it's time to move through the other fixes. I'd start with the force restart, as it resolves a surprising number of temporary glitches.
Perform a Force Restart
This is different from a normal power-off and is the go-to first step for an unresponsive phone. On the Xperia 1 VI, you press and hold the Power button and the Volume Up button together for about 10 seconds or more.
Keep holding until you feel the phone vibrate and see the Sony logo appear. This clears the phone's working memory and can kick it out of a frozen state without affecting your data.
Inspect Your Charging Setup
Since Sony doesn't include a charger in the box, you might be using an older or underpowered one. The Xperia 1 VI supports up to 30W wired charging, but it needs a USB-PD 3.0 compatible charger to hit that speed.
Try a different high-quality USB-C cable and a different wall adapter. Plug it directly into a wall outlet, not a computer or a car charger, for the most reliable power. Look closely at the phone's USB-C port for any packed-in lint or debris that could be blocking the connection.
A can of compressed air can gently clear it out. I've seen a single speck of pocket lint prevent charging entirely.
Boot Into Safe Mode
If the phone turns on but gets stuck on the Sony logo or crashes during boot, a recently installed app could be the culprit. Safe Mode temporarily disables all third-party apps.
First, force the phone off by holding Power and Volume Up until it vibrates and shuts down. Then, press and hold the Power button until you see the Sony logo. As soon as the logo appears, release the Power button and immediately press and hold the Volume Down button.
Keep holding Volume Down until you see "Safe mode" in the bottom corner of the screen. If the phone boots successfully this way, you'll know an app is causing the problem. You can then restart normally and start uninstalling recent apps one by one.
Try Recovery Mode Options
If Safe Mode doesn't work or you can't get to it, you can try accessing the Android Recovery menu. Turn the phone off completely. Then, press and hold the Power button and Volume Down button together.
Hold them until the phone vibrates and the Sony logo appears, then release both. You should see an Android robot with an exclamation mark. Press the Power button once, then tap Volume Down to highlight "Wipe cache partition." Press the Power button to select it.
This clears temporary system files that can sometimes become corrupted. It doesn't delete any personal data like photos or messages. After it completes, select "Reboot system now."
Consider a Software Repair
For more serious software corruption, you might need to reinstall the device software. Sony provides a free tool called Xperia Companion for Windows and Mac. Install it on a computer and connect your turned-off Xperia 1 VI with a USB cable.
Hold the Volume Down button while connecting the cable to force the phone into flash mode. The software should detect it and give you an option for "Software repair." This will reinstall a fresh version of Android, so back up first if you can.
It's a more thorough fix than a cache wipe but less drastic than a full factory reset from the phone's menu.
Check for Physical Damage
Think back to whether the phone has had any recent impacts or exposure to liquid. Even a small drop can sometimes disconnect an internal ribbon cable for the screen or battery.
While the Xperia 1 VI is rated IP65/IP68 for dust and water resistance, that protection can degrade over time or if the phone has been previously repaired. If you suspect water damage, don't charge it. Leave it in a dry, warm place with the port facing down for at least 48 hours before trying to power it on again.
Understand the Battery Care Feature
Your Xperia has a feature called Battery Care designed to extend the battery's long-term health. It can limit charging to 80% or 90% overnight and learns your charging habits.
If you're checking the phone early in your routine, it might genuinely be at a lower charge than you expect. You can check or disable this in Settings > Battery > Battery Care once the phone is on. For troubleshooting a phone that won't turn on at all, it's better to temporarily use a charger without this smart limiting if possible.
When All Else Fails
If the phone shows absolutely zero signs of life, no vibration, no flash of the screen, no charging light even after hours on a known-good charger, the issue is likely hardware. It could be a deeply discharged and failed battery, a problem with the main board, or a damaged internal component.
At this point, the next step would be contacting Sony support or a reputable repair shop that has experience with Xperia devices. They can perform a proper diagnostic to see if the phone is receiving power internally and pinpoint the faulty component.