How to load s3 private checkpoint with strategy.load_checkpoint outside of fit function

[PososikTeam]

I try to use pytorch-lightning fuction to load s3 checkpoints instead boto3. So i check trainer.fit(model, s3_path) and it's works great even with private s3 bucket, beacuse it's automatically use env aws variables. Inside trainer.fit(model, s3_path) it use next code inside trainer.connectors.checkpoint_connector.py

        with pl_legacy_patch():
            loaded_checkpoint = self.trainer.strategy.load_checkpoint(checkpoint_path)
        if any(key in loaded_checkpoint for key in DEPRECATED_CHECKPOINT_KEYS):
            raise ValueError(
                "The checkpoint you're attempting to load follows an"
                " outdated schema. You can upgrade to the current schema by running"
                " `python -m pytorch_lightning.utilities.upgrade_checkpoint --file model.ckpt`"
                " where `model.ckpt` is your checkpoint file."
            )
        return loaded_checkpoint

But when i run my simple_example:

from pytorch_lightning.utilities.types import _PATH
from pytorch_lightning.utilities.migration import pl_legacy_patch
from pytorch_lightning import Trainer


if __name__ =='__main__':
    trainer = Trainer()
    with pl_legacy_patch():
            loaded_checkpoint = trainer.strategy.load_checkpoint('s3://try_download_s3/4-8445.ckpt')

it's fail with next errors:

Traceback (most recent call last):
  File "download_checkpoints.py", line 20, in <module>
    loaded_checkpoint = trainer.strategy.load_checkpoint('s3://ml-mage/try_download_s3/4-8445.ckpt')
  File "lib/python3.8/site-packages/pytorch_lightning/strategies/strategy.py", line 317, in load_checkpoint
    print(self.checkpoint_io.load_checkpoint(checkpoint_path))
  File "lib/python3.8/site-packages/pytorch_lightning/plugins/io/torch_plugin.py", line 86, in load_checkpoint
    return pl_load(path, map_location=map_location)
  File "lib/python3.8/site-packages/pytorch_lightning/utilities/cloud_io.py", line 49, in load
    return torch.load(f, map_location=map_location)
  File "lib/python3.8/site-packages/torch/serialization.py", line 607, in load
    return _load(opened_zipfile, map_location, pickle_module, **pickle_load_args)
  File "lib/python3.8/site-packages/torch/serialization.py", line 882, in _load
    result = unpickler.load()
  File "lib/python3.8/site-packages/torch/serialization.py", line 875, in find_class
    return super().find_class(mod_name, name)
ModuleNotFoundError: No module named 'src'

Please help how to load checkpoint with pytorch-lightning fuctions?